Feline Leukemia Virus(FeLV) & Feline Immunodeficiency Virus (FIV)

Feline leukemia virus (FeLV) and feline immundeficiency virus (FIV) are two important contagious viral organisms that infect cats.  They affect the immune system and can cause increased susceptibility to many diseases and cancers (including lymphoma, squamous cell carcinoma, and several forms of leukemia).  FeLV infection is also associated with bone marrow disorders (anemia, myelodysplasia) and reproductive disorders.

Feline Leukemia Virus (FeLV)

Feline leukemia is transmitted both from cat to cat and from mother to offspring. The most common route of infection is through contact with infected body fluids (blood, saliva, etc.).   Cats exposed to these viruses may 1) be able to fight off the infection, 2) develop a hidden/latent infection, or 3) become infected and continuously infectious to other cats.  Those animals that have a latent infection cannot transmit FeLV to other cats unless stress or immunosuppression (such as the administration of steroids) places the virus back into circulation.   Outside the cat, the virus dies quickly in a dry environment.   The virus can survive twenty-four to forty-eight hours in a moist environment and so can potentially be transmitted to another cat by shared litter boxes and food dishes.

The screening test for FeLV infection is a blood test called an ELISA antigen test.  All positive tests should be confirmed with either the submission of another more specific test called an IFA test or by repeating the ELISA test in three to four months.   To confirm a negative test after exposure, an ELISA antigen test can be repeated in three months.  It is important to realize that cats with latent infection will test negative, but may still develop associated disorders later in life.  Vaccination does not interfere with testing.

Feline Leukemia vaccinations have been available for many years.   The vaccine is not one hundred percent effective.  The vaccine has also been associated with the development of an aggressive cancer at the site of vaccination called fibrosarcoma.  The risk of vaccination should be weighed against the risk of exposure and infection.  If vaccination is to be performed, test before vaccinating, as there is no benefit to vaccinating a FeLV positive cat.

Feline Immunodeficiency Virus (FIV) 

There are five different types of FIV:  A, B, C, D and E.  In the United States, most cats are infected with subtype A on the West Coast and B on the East Coast.  The most common mode of transmission is through saliva and bite wounds.  The majority of FIV-positive cats are outdoor males.  FIV survives outside the body for only a few minutes and is unlikely to be transmitted by shared litter boxes and food dishes.  Most infected cats will test positive within sixty (60) days after exposure.  Kittens can test positive due to maternal antibodies, but usually become negative later.  Kittens should be re-tested at six (6) months of age.

FIV infection is associated with neurologic disease, chronic renal failure, cancers (especially lymphoma and squamous cell carcinoma), stomatitis (mouth and gum disease), respiratory conditions, diarrhea, urinary disorders, and wasting syndromes.  

Unlike the FeLV test, the FIV test is an antibody test instead of an antigen test.  The viral antigen levels in FIV infection are usually too low to detect.  Additionally, antibody levels wax and wane.  They can be detected as early as two (2) weeks after infection.  IFA and ELISA are used as the methods for the screening tests.  FIV negative cats are likely to be uninfected.  A Western blot test is the confirmatory test.  Annual FIV testing is recommended for at risk cats i.e., outdoor cats and those living with FIV positive cats.   

An FIV vaccine is available.  It is a killed vaccine composed of subtype A & D.  It is reported to be eighty-two (82%) percent effective at preventing subtype A.   There are no data as to the efficacy against subtype B, which is the subtype found on the East Coast.  Vaccinated cats will test positive on all tests including Western Blot tests.  Vaccination cannot be differentiated from infection on the FIV antibody test.  Kittens from vaccinated queens can test positive until eight (8) weeks of age.  Only those at high risk should be considered for vaccination and they should be tested as negative before vaccination. Given that any vaccinated cat may potentially always subsequently test positive for FIV on all available tests, cats receiving an FIV vaccine should be microchipped or in some other way permanently identified – just in case they roam or get lost and end up in an animal shelter which tests for FeLV/FIV! 

Treatment for FIV and FeLV

Treatment for FIV and FELV positive cats typically targets the treatment of the secondary diseases and supporting the immune system.  Good nutrition and management are important components of therapy.  Immunodulators such as the staphylococcal protein A, Acemannan, and interferon alpha have been used with varying degrees of anecdotal success.  Antiviral drugs such as AZT are also available.  Only the antiviral drugs have clinical data to support their efficacy but unfortunately have been found to cause adverse side effects.

Diabetes Mellitus

Diabetes mellitus is a common disorder of both cats and dogs. While the exact sequence of events leading to development of diabetes may be somewhat different, the signs of the disease and its treatment remain very similar for both species.

Diabetes mellitus, or sugar diabetes, is a hormone disorder which causes a persistent elevation of blood and urine sugar called glucose. Persistent glucose elevations induce the signs of the disorder, which are excess thirst and increased urination. Insulin therapy remains the most common and effective treatment for cats and dogs with diabetes mellitus. Insulin is a hormone normally produced by the body and released into the bloodstream to prevent elevations of blood and urine sugar. Insulin therapy involves the pet owner injecting the hormone under the skin with a needle and syringe once or twice daily. There is no form of insulin available that can be given by mouth or added to the pets food.

Important facts regarding diabetes mellitus in pets:

1. With few exceptions, diabetes mellitus is a permanent disorder which requires treatment for the rest of your pet's life.
2. With proper treatment, diabetes can be effectively controlled over the normal lifespan of your pet. In addition to insulin therapy, effective treatment may include strict diet and exercise regimens, use of special diets, administration of oral hypoglycemic drugs and frequent followups with your veterinarian.
3. Left untreated, diabetes mellitus is fatal. Additionally, diabetes can cause cataracts, severe metabolic toxicity (ketoacidosis), nerve and muscle weakness, rapid weight loss, increased susceptibility to infection, and damage to the kidneys, eyes, and brain.

A close cooperative effort with your veterinarian is critical to successful regulation of your pet's diabetes. The number of and length of visits to your veterinarian's hospital and the annual costs of your pet's health bills will increase. What your pet gains from this cooperative effort is good health with a minimally restrictive lifestyle and a normal lifespan. Treatment of a pet with diabetes is not easy and certainly not practical for every pet owner. However, the treatment is very rewarding and worthwhile if the time and effort required can be provided.

Addison's Disease

Addison’s disease is a condition that occurs when the adrenal glands stop producing hormones.   The symptoms tend to be non-specific and may include lethargy, weakness, and gastrointestinal upset.  It is common for the signs to wax and wane over a period of time before a diagnosis is made.

Some dogs with Addison’s disease are not diagnosed until they are critically ill (an Addisonian crisis).  This life-threatening stage of the disease results in collapse and shock—it must be treated as an emergency.

There is no cure for Addison’s disease, but it can usually be treated with replacement hormones, giving the dog a normal life span and quality of life.  It is diagnosed (and monitored, once treatment has begun) with blood tests.  The drugs most commonly used to treat Addison’s disease are called prednisone, Florinef, and DOCP—a dog may require only one or a combination of these medications.

Most cases of Addison’s disease are diagnosed in middle-aged dogs (the median age of diagnosis is 4-5 years), although it has been reported in animals as young as 2 months and as old as 14 years.  Female dogs are disproportionately affected (about 70% of cases), with sexually intact females at greatest risk and intact males at the lowest risk.   About one third of cases are mixed-breed dogs, but there appears to be some breed predilection, with poodles, Portuguese water dogs, Great Danes, Leonbergers, German shepherds, and rottweilers among those thought to be predisposed.

The prognosis for dogs diagnosed with Addison’s disease is excellent as long as they are carefully managed.  They can be expected to live out a normal life span with few if any limitations, but they do require life-long medication.

The typical signs of Addison’s disease are vague and non-specific and are often seen in other, more common disorders.  They can also vary widely in severity.  Affected dogs may show lethargy, anorexia, vomiting, diarrhea, weight loss, shaking/shivering, or excessive thirst and urination.  A characteristic feature of Addison’s is that the signs tend to follow a waxing and waning course and improve dramatically when the animal is treated with fluids and/or steroids.

Additional clinical signs that your veterinarian may observe on physical examination include: poor body condition, weakness, dehydration, weak pulses, a slow heart rate, and blood in the stools.  Blood work may indicate:  anemia, electrolyte imbalances (i.e., elevated potassium, low sodium, and low chloride), low blood sugar, elevated calcium, acidosis, and elevation of liver and kidney values.

Approximately 35% of dogs with this disease present in what is known as Addisonian crisis; this is a true emergency and immediate treatment is required to save the dog’s life.  These animals have the classic signs of shock: mental dullness, pale mucous membranes, weak pulses, and cold extremities.  In addition, they have an abnormally slow heart rate due to elevated blood potassium levels.

Mechanisms and Causation

The adrenal glands are paired glands that sit near the kidneys.  They are made up of two layers, an outer cortex and an inner medulla, that are structurally and functionally distinct.  The cortex produces three types of hormone: mineralocorticoids, glucocorticoids, and androgens, which are collectively known as steroids.  Addison’s disease occurs when the adrenal cortices are destroyed and the body loses its ability to produce these hormones; the medical term for it is hypoadrenocorticism.   There may be no clinical signs of disease until 90% of the adrenal cortex has ceased to function.

It is not well understood what causes the destruction of the adrenal cortices.  In most cases the cause is thought to be autoimmune (the result of an over-active immune system) or idiopathic (unknown).  Rarely, there may be other causes, such as bleeding disorders, infectious disease, or metastatic cancer.  Addison’s disease may also occur when a dog that has being treated for a long period of time with steroids is abruptly withdrawn from the medication or when a drug called Lysodren is given, however, this form of the disease is usually reversible (fewer than 2% of these cases are permanent).

Diagnosis

While the clinical signs may strongly suggest Addison’s disease, it can be definitively diagnosed only by means of a blood test called an ACTH stimulation test.  A baseline blood sample is drawn, then ACTH (a hormone that stimulates the adrenal glands) is given by injection and a second blood sample is taken 1-2 hours later.  The blood samples are analyzed to determine the level of adrenal hormone present; if the dog has shown little or no response to the ACTH administration, the test confirms Addison’s disease.

Treatment

If an animal presents in Addisonian crisis, shock (i.e., low blood pressure and low blood volume) poses an immediate threat to his life and must be treated before the underlying disease is addressed.  The most critical aspect of the initial treatment is intravenous fluid replacement; this restores blood volume and pressure and also helps to correct some of the biochemical abnormalities.  An ACTH stimulation test should also be conducted at this time—it can be done concurrently with the fluid therapy.  Fluids are administered at a high rate (shock dose) for approximately the first hour, then lowered to a rate determined by individual needs once the dog’s heart rate, pulse quality, and attitude improve.  The dog often will improve rapidly with fluid therapy.  The heart rate and rhythm, electrolytes, and other parameters will begin to normalize over the next 12-24 hours.  During this time the dog will also begin to be treated with injectable steroids.  Most dogs that present to the clinic in a crisis will spend at least 24-48 hours in the hospital; the length of hospitalization will depend on the individual dog’s condition and response to therapy.

Maintenance treatment for Addisonian patients consists of life-long hormone replacement to compensate for the body’s inability to produce glucocorticoids and mineralocorticoids.  For dogs that present in crisis, this treatment can begin once they are stable and able to take food and water by mouth—for the others, it begins as soon as they are diagnosed.  Glucocorticoid replacement is accomplished with prednisone, given orally on a daily basis. 

There are two options for mineralocorticoid replacement, an oral medication called fludrocortisone (Florinef) and an injectable one called DOCP (Percorten-V).  Florinef is usually more expensive than DOCP.  Florinef must be given daily, and it has some glucocorticoid activity in addition to its mineralocorticoid activity, so dogs that take it may or may not need to take prednisone as well (about 50% of dogs will need prednisone).  It is not unusual for a dog’s Florinef dose to rise gradually over the first 2 years or so of treatment, but it usually stabilizes after that.  DOCP injections are given approximately every 25 days, but DOCP has exclusively mineralocorticoid activity, so dogs that take this drug will usually require daily prednisone as well.  The response to DOCP is variable, so the actual dosing schedule must be tailored to the individual dog.

Stressful situations (e.g., travel, hospitalization, surgery) increase the body’s need for glucocorticoids, so you should keep a small supply of prednisone on hand to use as needed (your veterinarian will advise you on the appropriate dose for your dog).

Monitoring

Your veterinarian will recommend a specific monitoring plan for your dog, but typically it will include blood work every 5-7 days until the electrolytes have stabilized in the normal range (or for the first month if you are using DOCP), then monthly (or at the time of each subsequent DOCP injection) for the next 6 months and every 3-6 months thereafter.

An Addisonian dog needs to be carefully managed and faithfully medicated for the rest of his life, but as long as you do this, his prognosis is excellent for a normal lifespan and quality of life.

Ultrasound Exams in Dogs and Cats

One of the most commonly performed diagnostic procedures at SouthPaws Veterinary Specialists and Emergency Center is the ultrasound examination. Advanced training and experience are required to accurately interpret the results of this type of imaging. At SouthPaws, our ultrasound examinations are typically performed by our board-certified radiologists.

The ultrasound exam begins by placing the tip of a transducer probe against the moistened skin of the patient. High frequency sound waves are introduced into the body tissues and reflected back into the probe to develop visual images of the internal organs. The examination is painless, usually requires no sedation or anesthesia, and typically takes less than half an hour to perform.

Ultrasound examination is useful in:

1. Evaluating diseases of tissues including the liver, kidneys, spleen, bladder, prostate, pancreas, adrenal glands, thyroid and parathyroid glands, muscles, tendons, and lymph nodes.
2. Evaluating tumors and masses.
3. Evaluating fluid buildup in body cavities (chest, abdomen, heart sac), in internal organs (gastrointestinal tract, urinary tract, uterus), and in cysts or abscesses.
4. Evaluating heart disease (an ultrasound examination of the heart is often called an echocardiogram).
5. Evaluating structures within and behind the eye (retinal detachments, tumors, abscesses, and enlargement or protrusion of the eye).
6. Guidance of biopsy instruments and catheters (fine needle aspirates, liver and kidney biopsies, pericardial, abdominal and thoracic drainage).

Because of the non-invasive nature of ultrasonography, it(often in conjuction with needle aspiration/cytology) has replaced the need for exploratory surgeries in many patients.

We urge you to discuss the possible advantages of an ultrasound examination with your local veterinarian to determine if illness in your pet may be best evaluated by this type of imaging.

Cancer in Pets

As our pets are living longer and healthier lives, we are seeing more and more develop heart disease and cancer - just like people. Dogs, cats and exotic animals all get many different types of cancer. Some kinds of cancer are curable, some are treatable, and for some we can provide comfort care.

Whether a treatment or therapy is appropriate for your pet with cancer depends on:

1. the type of cancer (based on biopsy or cytology)
2. the grade or stage of the cancer (how aggressive or fast-moving it is)
3. the location

In order to be able to give you and your pet the best options, a definitive diagnosis and a staging workup must be performed. These procedures involve getting a biopsy or aspirate of the tumor, and examining for spread (metastatic sites) for that particular form of cancer. We can use palpation, ultrasound, radiographic studies and needle aspirates to look at the lymph nodes, lungs, spleen, liver and other metastatic sites. We will also need to know how the rest of your pet's body is working - are there problems with the kidneys or liver, is there diabetes or heart disease? These other diseases may be more serious than the cancer, or may change what forms of therapy are appropriate.

Once we have a complete understanding of your pet's health and type of cancer, we can design a treatment plan that fits your needs best. Cancer therapy in pets can include surgery, medications, chemotherapy, radiation therapy, immunotherapy, nutritional recommendations, combination therapies, and palliative care.

Chemotherapy is used in pets if cancer involves more than one part of the body or if the cancer is one which is likely to metastasize (spread). Some cancers are very responsive to chemotherapy (80-90%), while others have no response to chemo, and so therapy is not recommended. Depending on the type of cancer, different drugs or combinations of drugs are used. Pills, injections, intralesional therapy, and IV infusions can all be given to dogs and cats, with most treatments performed on an outpatient basis.

In general, most pets receiving chemotherapy experience minimal side effects. Some even seem to have more energy and an improved appetite. Some drugs can cause nausea, vomiting or diarrhea in sensitive pets, but these side effects can typically be prevented. Low white blood cells counts are a more common problem, so before chemotherapy is given, complete blood counts are monitored. Hair loss is uncommon in most pets. Pets receiving chemotherapy should be able to perform and enjoy all of their normal activities.

Staging Cancer

Sarah E. Sheafor, DVM, ACVIM - Oncology

Often when we are presented with a patient with a "lump" or "cancer," we have to decide not only how to obtain a definitive diagnosis, but also how to determine whether the cancer has spread to other parts of the body. Depending on the type and location of the tumor, different staging protocols are indicated. The first rule of thumb is not to perform any test whose results will not change the diagnosis, prognosis, or therapeutic plan.

Mammary tumors

In both dogs and cats, chest radiographs, assessment of regional lymph nodes via palpation, and aspiration or biopsy of any enlarged nodes, as well as a complete assessment of all other mammary tissue comprises the minimal evaluation of a patient with mammary cancer. CBC and profile will give any assessment of overall organ function. For most dogs and cats, needle aspiration or incisional biopsies are not performed, but instead, the entire tumor is removed surgically. Inguinal lymph nodes should be removed at the same time as the caudal inguinal mammary gland, and should be biopsied. Axillary dissection, in the face of no palpable axillary lymph node enlargement, is probably not necessary. Once biopsy results from the primary tumor and from any involved lymph node are available, the need for additional surgery or adjuvant therapy (chemotherapy) can be discussed.

Perianal Tumors

These tumors are common in dogs and exceptionally rare in eats. Chest radiographs, abdominal ultrasound to assess sublumbar node status, and serum chemistry to assess calcium values are the essential components of a staging workup of a patient with a large, ulcerated, or invasive perianal mass or with any anal sac mass. Anal sac tumors metastasize early to the sublumbar lymph nodes. If any enlargement of these nodes is noted on abdominal ultrasound, they can be aspirated or a plan can be made to have these nodes removed at the time of the definitive surgery for the anal sac tumor.

Lymphoma (dogs)

The complete staging workup includes a CBC, profile, lymph node biopsy, chest radiographs, abdominal ultrasound or radiographs to evaluate the liver and spleen, and a bone marrow aspirate. The stage of canine lymphoma, however, is very rarely of prognostic significance in dogs with multicentric lymphoma. The academic benefits of a staging workup must be balanced against the costs of this evaluation in a dog needing life-long chemotherapy. A modified staging protocol that is practical for the majority of dogs with multicentric lymphoma is a lymph node aspirate for diagnosis, and a CBC, profile, and urinalysis to assess overall health, and to have a baseline for chemotherapy planning. Should significant abnormalities be noted on history, physical examination, or on the lab work, additional testing to rule out concurrent diseases or organ dysfunction may be needed.

Soft Tissue Sarcomas

Chest radiographs are the essential components of a staging workup for dogs and cats with soft tissue tumors. For certain patients, radiographic imaging, CT scanning or MRI of the primary tumor is helpful in planning an appropriate treatment of aggressive surgery and/or radiation therapy. These studies are helpful in finding out how extensive and invasive the tumors is, and can sometimes change therapeutic recommendations. Grading (determination of the aggressiveness of the tumor) can only be determined via excisional or incisional biopsy. Careful planning of the biopsy or first surgery performed can create the difference between an easily cured tumor and one that is incurable or that requires extensive follow up therapy.

Cutaneous Mast Cell Tumors (dogs)

The ideal staging workup for dogs with cutaneous mast cell tumors depends on the grade of the tumor, as well as the type of therapy recommended. In cases of an incompletely-resected, grade I or II mast cell tumor, where the owners are contemplating extensive surgery or radiation therapy, regional lymph node assessment/aspiration, +/-abdominal ultrasound (with any indicated aspirates are performed to try to be certain that the tumor is confined to the primary site. In dogs with grade III mast cell tumors, metastatic disease is expected, so chemotherapy should be recommended in addition to local therapy. A complete staging workup is not as essential in these patients, although routine blood work can provide helpful monitoring points.

Visceral Mast Cell Tumors (cats)

Cats with splenic mast cell tumors often have positive buffy coat smears. Once the spleen is removed, the buffy coat can become negative. There is no difference in survival times between cats with positive or negative buffy coat smears prior to surgery, but it can provide a useful monitoring test. CBC, chemistry and abdominal ultrasound are the staging tests typically needed in a cat with visceral mastocytosis.

Staging evaluations should be individualized to fit patient and client needs, as well as the type and location of the tumor. At SouthPaws Veterinary Specialists and Emergency Center, with our abilities to provide complete oncology services, patients can be properly diagnosed and staged to ensure that they have the best outcome possible. With adequate staging and client education, we can make certain that clients are aware of the nature and prognosis of their pet’s cancer, and have been given the best integrative approach to therapy.

Topics in Oncology: Osteosarcoma - An Oncologist's Perspective

Osteosarcoma is the most common primary bone tumor in dogs. It typically occurs in the long bones of middle-aged, large and giant breed dogs. The distal radius is the most common location for osteosarcoma. Dogs present with signs of lameness and swelling. A presumptive diagnosis is often made based on signalment, physical examination, and radiographic findings of a osteolytic, osteoproliferative or mixed bone lesion. Differential diagnoses for these lesions include other primary bone tumors (chondrosarcoma, fibrosarcoma, hemangiosarcoma), lymphoma or multiple myeloma of bone, tumors metastatic to bone (carcinomas), systemic mycoses, and bacterial osteomyelitis. Osteosarcoma can be definitively diagnosed via bone biopsy. Thoracic radiographs are an important part of the diagnostic workup, as 5%-10% of dogs will have visible metastatic lesions at the time of initial presentation. Routine screening of blood and urine are also essential to evaluate the overall health of the patient, and to determine the best therapeutic options.

Local treatment is the first step in therapy. Bone tumors are painful, and excision is the best way to relieve the pain. Amputation has long been the mainstay of therapy for osteosarcoma. Limb-sparing surgery for certain patients (based on size of tumor, extent of infiltration, and location of tumor) is also successful. Palliative radiotherapy is an option for dogs who cannot have amputations (eg., those with disabling orthopedic or neurologic conditions). Palliative radiation consists one to four treatments of megavoltage radiation. This therapy is effective at controlling pain in up to 70% of patients. The tumor is not affected, and the tumor-weakened bone may fracture as the patient uses the leg more normally. Regardless of the form of local therapy, if adjuvant therapy is not used, most patients succumb to metastases within 3-4 months. The one year survival of dogs treated with amputation alone is less than 10%.

Systemic therapy is effective in dogs with osteosarcoma, producing 40-60% in one year survival rates. We now have three standard treatment options for dogs with OSA, enabling us to pick the drug which best fits the patient's needs. The gold standard drug is cisplatin. Cisplatin is not a good choice for dogs with renal disease, or dogs with significant heart disease who cannot tolerate fluid diuresis. Cisplatin is given every 21 days as an intravenous infusion. Diuresis with saline is required both pre- and post-therapy meaning that displatin therapy requires a one day hospital stay. Carboplatin is the second-generation form of cisplatin. It is given as an IV bolus drug, so is appropriate for outpatient therapy. Carboplatin is less nephrotoxic than cisplatin, and doesn't require any diuresis. It is given every three weeks, as well. Four treatment cycles of cisplatin and carboplatin are ideal. Doxorubicin (Adriamycin) is also effective against osteosarcoma micrometastases. It is inappropriate for dogs with heart disease or those who may have occult cardiomyopathy (Dobermans). For osteosarcoma, it is given as a 30-40 minute intravenous infusion every two weeks for five treatments. Echocardiographic monitoring before the first, third and fifth treatments is recommended. All of these systemic therapies are available through the SouthPaws oncology service.

What is Feline Hyperthyroidism?

Feline hyperthyroidism is recognized as the most common endocrine disorder in the cat. In 97% of feline hyperthyroid cases, the cause is a benign tumor that over-secretes thyroid hormones, resulting in a multi-systemic disease. The total metabolism of the body is dramatically increased, making the body work much harder than normal. In the process, hyperthyroidism potentially masks certain underlying diseases like kidney failure. Clinical signs of hyperthyroidism vary from mild in the early stages, to severe or life threatening signs in the final stages. A thorough medical work-up is necessary to determine if the changes (weight loss, behavioral changes, ravenous appetite, vocalization, hyperactivity, rapid heart rate and/or murmurs, and kidney compromise to name a few) that you and your veterinarian have noted are due solely to hyperthyroid ism or are a part of other disease processes.

Options for Treatment:

Hyperthyroid cats can be treated in many ways including surgery, anti-thyroid medications (pills), intralesional ethanol injections, and injectable radiation therapy (I-131). Each approach has its pros and cons, but the consensus among veterinarians is that I-131 therapy is the curative treatment of choice for most hyperthyroid cats.

Surgery - may cure a hyperthyroid cat, but recurrence of the problem is common if only one thyroid gland is removed or if there is ectopic thyroid tissue in the chest cavity. If both thyroid glands are removed, the parathyroid glands may be damaged, requiring several days of hospitalization and/or monitoring to try to avoid a possibly fatal outcome. Older cats who develop hyperthyroidism may also be poor surgical/anesthetic candidates.

Medical Management - Methimazole is the most common drug, and usually controls hyperthyroidism, but does not cure it. Administration of pills or liquids twice a day for life is required – a difficult task in some cats. Transdermal formulations of these medications are effective in some but not all cats but also need to be given twice a day. Potential side effects of Methimazole include liver disease, bone marrow suppression, vomiting, diarrhea, poor appetite, skin problems, and immune-mediated disease. Regularly scheduled laboratory work is important to monitor for efficacy of Methimazole therapy and to identify any possible adverse effects.

Intralesional Injections of Ethanol - Using ultrasound guidance. This modality is only suitable for cats with very small thyroid masses. It requires anesthesia to perform, and complications include recurrence of hyperthyroidism, parathyroid damage, and nerve or laryngeal damage.

Radiation Therapy - with the injectable isotope I-131 cures almost all treated cats. Fewer than 5% of cats remain hyperthyroid and require a second treatment, while less than 5% become hypothyroid and then require daily thyroid hormone supplementation. I-131 therapy does not require anesthesia or surgery. The isotope is taken up by the hyperfunctional thyroid cells wherever they are located within the cat, but most normal thyroid cells and the parathyroid gland and other nearby structures are not affected. Although the injection is simple (subcutaneous single injection), cats will remain radioactive until the isotope decays. The Federal and State laws require us to "hold" a cat until radioactivity levels emitted are too low to be harmful (typically a matter of two to three days). Cats are kept in an isolation area here at SouthPaws, and cannot be visited, petted or held by their owners. We can provide food and water, and clean their litter boxes, but we cannot hold them either. Because of these isolation requirements, cats with serious non-thyroidal illnesses (heart failure, diabetes, chronic renal failure, etc.) are NOT good candidates for I-131 therapy.

Why Choose I-131?

• I-131 does NOT require anesthesia
• No surgery
• No risk of damage to the parathyroid glands
• No harmful side-effects
• Normal thyroid function returns in 30 to 180 days

Downloadable Forms:

• Referring Veterinarians Checklist for I-131 Therapy
• Client Checklist Preparing for I-131 Therapy

Radiation Therapy

What is it? Radiation therapy (megavoltage) is supplied by a Linear Accelerator. This device generates high energy photons or electrons used to treat many kinds of cancer. Radiation therapy is typically applied to one site in an attempt to provide local therapy (local control or cure) of a cancer that only affects one part of the body.

What is the goal? When choosing radiation therapy for any patient, we have to consider what the goals of therapy are – are we trying to "cure" or eradicate all local tumor cells, or are we trying to shrink a cancer to make it operable or more amenable to chemotherapy, or are we simply trying to make pain control easier?

Full course treatments. Radiation therapy is delivered to a total dose of between 45-54 Gray for most types of cancer. This dose is more than 500 times what a diagnostic xray (radiograph) would be so it cannot be tolerated by any normal tissue as a single dose. We divide up that dose into many "fractions" which are then delivered on a Monday-Friday basis until the total dose needed for that cancer’s control has been given. Radiation therapy is a key feature in the treatment of patients with the following cancers:

• Nasal carcinomas
• Nasal sarcomas
• Nasal lymphoma
• Laryngeal lymphoma
• Brain tumors
• Pituitary tumors
• Oral squamous cell carcinomas in dogs
• Skull tumors
• Incompletely excised (but not yet recurrent) mast cell tumors
• Incompletely excised (but not yet recurrent) soft tissue sarcomas (oral and other locations)
• Non-resectable plasma cell tumors

Treatment of these patients typically involves a CT-based 3D radiation treatment plan, and 15 – 18 treatments over a 3-4 week time period. Lymphoma/plasmacytoma therapy takes many fewer treatments as these tumor types are very sensitive to radiation therapy and we do not need to treat to as high a total dose.

Palliative/Short Course: Radiation therapy can also be used in palliative fashion to try to slow an aggressive/non-resectable tumor’s growth, to shrink an oral tumor, decrease the vascularity of a cancer, or to kill pain associated with a cancer such as the following:

• Oral melanoma
• Bulky soft tissue sarcoma
• Bulky carcinomas
• Oral squamous cell carcinoma in cats
• Osteosarcoma

Palliative radiation therapy may be given once only, or up to four times on a once-a-week basis depending upon the tumor type. A two dimensional radiation treatment plan is usually used for this type of patient (may be radiographic based, or CT based).

How is it performed? All radiation therapy requires perfect positioning of patients to avoid side effects to portions of the body that should not be in the treatment field! That means that each patient will have to be anesthetized for each therapy. Radiation therapy anesthesia protocols are designed for safety in repetitive use – often in an elderly patient population. Butorphanol, propofol and/or gas anesthesia are used to try to have patients back on their feet as quickly as possible. The treatment field may be shaved and marks placed on the skin during the first imaging session to be certain that the treatment field stays the same with each treatment.

Admitting patients: Patients for radiation therapy must first be seen by one of our oncologists to discuss treatment options, prognosis, and overall state of health. Imaging for treatment planning would be accomplished next so that a detailed treatment plan can be designed. Once imaging and treatment planning are complete, radiation therapy would typically be begun on a Monday (for full course treatments) – although schedules can be adjusted to meet patient needs. Clients can either drop their pets off for the day, or set up a defined time for radiation therapy. Pets must be fasted for at least 12 hours prior to their radiation therapy (due to anesthesia needs).

Side Effects: Radiation therapy cannot tell the difference between normal and cancer tissues – it simply kills cells as they divide. Since most cancers divide much faster than normal tissues, we get a selective effect on the cancer cells. We expect, however, to see side effects of radiation therapy. Acute (or short term) effects include loss of hair, moist desquamation of skin/mucus membranes (radiation burn like a blistering sunburn), and corneal irritation – if these tissues are in the treatment field. Common late side effects of radiation therapy include permanent hair loss, permanent hair color change, cataracts, retinal degeneration, keratoconjunctivitis sicca – again only if these tissues are in the treatment field. Some organs have more difficulties with radiation than others – eyes are clearly sensitive, but tubular organs (esophagus, colon, rectum, urethra) can also be – they could heal from acute radiation effects by scarring (stricture). The heart, lungs, kidneys and spinal cord can only tolerate a limited amount of radiation therapy – so we try to avoid these structures. Bone marrow is very sensitive to radiation if used in an "whole or half body" therapy. Bone density within a treatment field decreases. One in 10,000 patients could develop a bone tumor in a treated bone 5-10 years following therapy. The spinal cord and brain’s vasculature can also be sensitive to some types of radiation therapy (late effects). Because we want to minimize side effects, imaging and treatment planning are essential for most patients.

Symptom care for side effects

Dogs and cats getting full course radiation therapy WILL develop acute side effects. Palliative or short course radiation therapy rarely causes acute side effects other than the hair loss needed in order to shave/mark the treatment field.

Dogs with moist desquamation (cats more commonly get dry desquamation with dry flaky skin and itchiness) need to have their treatment sites kept clean and dry (with water – not other products). We try NOT to bandage as we don’t want dirt and moisture to build up – that means that E-collars are often necessary as a dog’s licking will only make the side effects worse. If a pet is scratching, sometimes T-shirts, socks or hobbles must be used to prevent self-trauma. Anti-inflammatories and rarely narcotics can be used to help through this time period. Typically, these radiation burns form in the second to third week of full course therapy, and then form crusts, and then the skin heals under the crusts. The whole process takes about 2-3 weeks.

Mucositis is seen when the gums, tongue, cheeks, throat or other mucus membrane-lined tissue is in the treatment field (often with nasal or oral tumors). The mucosa will get very red, and may ulcerate or blister during the second week of full course radiation therapy. Bad smell to the breath (halitosis), drooling, and difficulty eating can occur. Oral rinses are often helpful. Some cats and small dogs could require a temporary feeding tube if a large portion of their mouths are in the treatment field. Mucosa heals quickly following the conclusion of radiation therapy.

Ocular side effects are of concern if the eyes are in the treatment field. Acute side effects include dry eye and corneal irritation – so artificial tears and medicated ointments are often needed. Eyes are checked for corneal ulcer formation at least weekly if they are in the treatment field – but let your oncology nurse know right away if your pet is squinting, or if the eyes look abnormal to you at home. Late side effects of radiation (permanent keratoconjunctivitis sicca or dry eye, cataracts, and retinal degeneration can be irreversible side effects of radiation therapy if the eye gets full dose or even scatter radiation. It takes between 6-12 months for cataracts to form following radiation therapy – cataract surgery could be considered if the tumor is under control.

Certain types of delayed side effects are very dangerous or deadly (spinal cord malacia, kidney fibrosis or scarring, lung fibrosis, death of bone) so every effort to avoid late side effects is made in full course radiation therapy – the risks of developing these problems is small (5-10%). The multiple fractions of radiation therapy as well as careful treatment planning are the ways that we attempt to avoid late side effects.

What if patient also needs other types of treatment? If a patient has a type of cancer that would benefit from multimodality therapy (surgery, chemotherapy, etc), then there are additional timing concerns – healing from surgery may be altered based upon when radiation therapy is started. Some chemo drugs make anti-cancer activity of radiation therapy stronger – while some cause worsened radiation burns. Your SouthPaws oncology team will help to design the best treatment plan to take into consideration all of these variables for your patient.

WHAT'S A BAER?

A Brainstem Auditory Evoked Response is a neurodiagnostic test that records the response to an external auditory stimulus. In other words, it examines the ability of the animal's hearing receptor, auditory nerve, and auditory pathways in the brain to hear a noise that we make outside the animal's head.

The procedure is performed on a dog or cat that is sedated, because it is necessary for the animal to hold still while it is wearing a device that looks like a foam-rubber ear plug (where the sound comes from) in each ear, and to have some very small recording electrodes placed under the skin (these are EEG electrodes, and they record activity from nerve cells in the inner ear and the brain).

Young puppies can be safely sedated using acepromazine, morphine, and atropine, and although they remain sleepy for several hours afterward, they tolerate the sedation and the BAER very well. In advance of the appointment, the animals are fasted for 8 hours, then prior to sedation, it is weighed, a brief physical exam is performed, and the BAER follows. The test usually takes 5-10 minutes, once the animal is sedated.

For young adult animals, other sedatives are often used, but otherwise the process is the same. Except for being sleepy for a few hours, there are no side effects to the test, and it is safe for an animal of any age provided that it can be sedated. Some very ill animals have been tested without sedation, because they do not struggle with the ear pieces and electrodes.

The test works in the following way: An animal is sedated, the stimulating ear pieces are placed in the ear canals, and the recording electrodes are placed under the skin over the top of the head ("vertex"), and beneath each ear ("bullae"). The Dantex Cantata is the machine that coordinates the stimulus, which is a click of a given sound strength (usually between 80-130 decibels), and the recording period afterward.

Animals with normal hearing and normal brainstem function usually develop a characteristic set of peaks in response to the click - the earliest peaks on the screen represent activity in the hearing receptors, the acoustic nerve, and its collection of cell bodies called the ganglion, and the later peaks represent depolarization of neurons in the brainstem nuclei.

The BAER is an excellent "yes or no" test for congenital deafness - an animal either has a response that can be clearly seen on the screen, or it has a flat line response, showing that the hearing receptors are not operating at all.

In instances where an animal is believed to have severe brain disease, the BAER can sometimes provide evidence that the brainstem is not transmitting impulses properly. The test is performed in the same way, but the peaks are analyzed differently. Results are not always as "clear-cut" when the test is used for this purpose, but the BAER can provide evidence to help confirm brain disease, or in rare instances, to indicate "brain death" in a severely compromised animal.

Peripheral Neuropathy

Peripheral neuropathy is less commonly diagnosed in dogs and cats than is spinal cord or brain disease; perhaps it goes unrecognized or is mistaken for disease of other systems. Peripheral nerve disease can be categorized as a mononeuropathy (a single nerve is affected) or polyneuropathy (multiple nerves are affected). Further, problems related to peripheral nerves can involve sensory, autonomic, or motor segments. In this article, manifestations of peripheral motor nerve disease will be addressed.

Motor neuropathy is characterized by paresis, flaccidity, depressed or absent stretch and flexor withdrawal reflexes, and neurogenic muscle atrophy. Immature animals suffering from peripheral nerve disease frequently develop abnormal joint and limb deformities and contracture of muscles and tendons, and abnormal growth. Animals with motor neuropathy are often profoundly weak, and cannot support weight without assistance, but when held and supported, may have normal proprioceptive and postural reactions of the limbs. Sensory abnormality may accompany motor nerve disease, but frequently sensation remains normal. In response to skin-pinch tests, these animals may vocalize or otherwise indicate that they perceive pain, but are unable to withdraw the stimulated limb. When motor nerve disease affects the distal extremities more than proximal limb or torso muscles, animals often crawl, keeping joints flexed, and advancing limbs from the shoulder or hip without extending carpal or tarsal joints.

Motor neuropathy is most often seen affecting one or more limbs, but can a ffect cranial nerves, eg., III, IV, VI, VII, IX, X, XIII - causing signs of pupil or eye position abnormality, facial paralysis, voice change, coughing, gagging or swallowing disorders, or megaesophagus. Dysuria occasionally results from peripheral nerve disease, and may involve detrusor or sphincter muscles, or both.

Motor nerve mono - or polyneuropathy can be further characterized according to location and etiology. For example, the cranial neuropathy most often seen in small animals is facial nerve paralysis (cranial nerve VII palsy). Animals with peripheral VII disease (unilateral or bilateral) are unable to close the eyelid or have a drooping lip, but do not have postural or proprioceptive deficits, paresis, or altered reflexes in their limbs. Sialosis and dropping of food when eating are commonly seen. This neuropathy frequently occurs bilaterally, and often one side of the face will be affected days or weeks before the other. As recovery occurs, eyelid function may return to normal, and the formerly drooping lip may become contracted. A pure cranial nerve VII palsy rarely results in abnormality of the cornea; if a corneal ulcer is discovered, or if the animal seems to lack corneal sensation, it should be carefully examined for polyneuropathy. Seventh nerve palsy is accompanied by lack of tear function only in rare instances. Causes of facial nerve palsy include endocrinopathy (eg., hypothyroidism, Cushing’s disease), middle ear disease (infection, tumor, trauma), or inflammation (viral, bacterial, fungal, protozoal, other) and there is also idiopathic facial palsy seen in dogs, where no underlying cause is found. In these dogs, signs often resolve without treatment. If underlying disease is discovered and treated, nerve function usually returns. Even without return of nerve function, most animals will adapt to lack of ability to close the eyelid, and drooling and food-dropping eventually abate. Disorders of swallowing, gagging, laryngeal movement, and esophageal motility usually are due to peripheral motor nerve dysfunction without sensory abnormality. The most common of these neuropathies is laryngeal paralysis (unilateral or bilateral). Laryngeal neuropathy has been reported as an inherited disease in several breeds, as well as a result of trauma, endocrinopathy, intoxication, compression, inflammation, or other disease of the recurrent laryngeal nerve (a branch of the vagus nerve). Megaesophagus is a common problem in dogs, but is less often caused by pure peripheral nerve (vagal) disease than by disease of muscle or of motor end plate (myopathy or myasthenia gravis).

It should be noted that in all instances, when peripheral disease of the cranial neves is present, the patient is normal in other respects - alert, able to walk, and lacking deficits in proprioception, postural reactions or reflexes. If cranial neuropathy is accompanied by changes in consciousness, respiratory pattern, heart rate, or sensory function, a central disease of the brainstem should be considered.

Motor nerve disease affecting limbs can also be categorized as to nerve distribution and etiology. In general, degenerative, inflammatory, toxic, endocrine, and paraneoplastic neuropathies affect the animal symmetrically, and often the hind limbs show signs before forelimbs. For example, botulism, tick paralysis, diabetic neuropathy, hypothyroid neuropathy, acute canine idiopathic polyradiculoneuropathy (ACIP or of "Coonhound Paralysis"), congenital and inherited neuropathy, paraneoplastic neuropathy associated with insulinoma, lead toxicosis and antineoplastic drug-induced neuropathies tend to affect both hind limbs, and progress symmetrically. By contrast, traumatic neuropathy (avulsion, transections from bone fracture or other injury, injection neuropathy, lymphosarcoma of nerve roots or vertebrae often affect nerves of only one limb, or of a portion of the limb. When diffuse or multifocal peripheral nerve disease is present, inflammatory disease (neosporum caninum, distemper, fungal disease, "allergic" neuropathy) or diffuse neoplasia (lymphoma, malignant histiocytosis) may be more likely than the differentials above, although differential diagnoses may include all of the above.

Electrodiagnostics (EMG, nerve conduction velocity tests, repetitive stimulations) can help to define whether and which muscles are denervated, whether some or all nerve fibers are affected, and whether the disease affects myelin, axons, or both. Further, biopsy of muscle and nerve can assist in characterizing the disease. Peripheral nerve diseases can be benign, in that with time and treatment, many animals will recover from them. This is most true of inflammatory and toxic neuropathies. When diffuse disease is present, and when it involves respiratory muscles or causes megaesophagus, pneumonia may complicate recovery. Appropriate monitoring and treatment of these animals will require intensive nursing care in the hospital. Recumbent animals are also susceptible to development of decubital sores and secondary infections of skin, and to urinary tract infections. Recovery time from peripheral motor neuropathy is variable, but may be prolonged. Owners of animals with these problems may need encouragement to continue treatment. Physical therapy may be of great benefit, to help avoid complications listed above, and in assisting the animal to regain strength.

Cranial Cruciate Ligament Rupture

Dog and cat knees are similar to humans. For example, knees have five ligaments, two menisci, a knee cap, and joint cartilage. The ligament most commonly affected in dog and cat knees - the cranial cruciate ligament - is the same ligament most commonly damaged in professional athletes. Dogs and cats usually tear this ligament when out running around, or sometimes when landing wrong after a jump.

The cranial cruciate ligament is a large, strong ligament located within the knee joint. It is not actually a single structure, but is, in fact, made up of a bundle of individual fibers tightly bound together to form the ligament. Most of the time when the ligament is injured, it is completely torn in half. Sometimes, though, only a portion of the ligament will tear. Though only a portion of the ligament may be torn, the whole ligament is damaged.

When a cranial cruciate ligament is torn, it causes sudden pain and often results in the pet holding its leg up. It also causes an instability in the knee joint. The pet may put the leg down and start using it within a day or so, but will continue to limp for several weeks. Normally, at the end of several weeks, the initial pain subsides and the pet is willing to use its leg more; however, the joint remains unstable. Every time the animal puts weight on the leg, the tibia (shin bone) slides forward in relationship to the femur (thigh bone). This abnormal motion causes wear and tear on the joint cartilage, causing pain and leading to arthritis. This motion can also put excessive stress on the menisci (C shaped pieces of cartilage within the knee joint), causing damage or tearing.

Surgery is the only corrective measure for cranial cruciate ligament injuries. Many surgical procedures have been tried on people and animals during the last 60 years; however, most orthopaedic surgeons agree that the procedures are not as successful as they would like. Knees that suffer this injury are never completely normal even after surgery is performed. Surgery does, though, stabilize the knee, allowing it to regain normal motion and thereby reducing the formation of arthritis. Surgery has been and remains the treatment of choice for this injury. If surgery is not performed, progressive arthritis will occur and the lameness will worsen with time.

There are many different ways to stabilize a knee with a cruciate ligament injury. TPLO and TTA surgeries are the most commonly performed CCL surgeries at SouthPaws. The majority of animals will regain normal or near normal use of their leg after the surgery and after a period of rehabilitation and physical therapy..

Tibial Plateau Leveling Osteotomy

Dr. Barklay Slocum developed this sophisticated surgery for the treatment of a tear or rupture of the cranial cruciate ligament (CCL) in dogs. Veterinarians around the world are being specially trained and certified to perform this procedure. Because this surgery is so successful, it is our belief that it will replace all other surgeries performed for this condition.

Dogs normally have a downward slope on the top part of their shin bone (tibia) from front to rear. The degree of this slope varies from dog to dog. It has been found that the steeper (greater) the slope, the higher the incidence of CCL tear (known in humans as ACL tear). The normal function of the cruciate ligaments is to keep the thigh bone (femur) sitting directly on top of the shin bone. When the cranial cruciate ligament tears, the thigh bone slides off the top of the slope of the shin bone towards the back (downhill) side of the slope. Every time the dog puts weight on the leg, the thigh bone partially "dislocates" as it slides down the slope. This causes pain, instability (like a "trick knee" and eventually irreversible arthritis.

The TPLO surgery levels the slope so when the dog puts weight on the knee, the thigh bone remains centered on the top of the shin bone. Technically speaking, an x-ray of the shin bone is taken and the angle of the slope is measured. An incision is made in the skin along the inside of the knee and the top of the shin bone. Another small incision is made farther down the shin bone. A small "key hole" incision is made into the joint, then the meniscus is also inspected for tears. If found, these tears are removed – similar to a person having the torn cartilage in their knee removed. Next, a jig is placed and, using a very specifically designed nitrogen-driven bone saw, a "C" shaped cut is made in the top part of the shin bone. A calculation using the preoperative degree of slope is then made and the top (cut) part of the shin bone is rotated so that the slope in the bone becomes level. A metal plate and six screws are inserted to hold the bone in place. The entire leg is then bandaged to keep post operative swelling to a minimum. This bandage is removed prior to discharge from the hospital. A nurse will meet with you at the time of discharge to review all home care instructions and also to instruct you in a very simple physical therapy program designed to enhance return of function.

The bone heals in approximately eight weeks and during this post-operative period, exercise must be limited. Patients are not permitted to go up and down stairs, jump on furniture, play with other pets, run around the house, or be off-leash outside. Skin sutures are removed two weeks after surgery and at that same time, a nurse will evaluate the healing progress. Eight weeks post-operatively, we take an x-ray to confirm that bone healing has occurred. If it has in full, exercise can be resumed. We do not remove the plate and screws.

Previous surgeries designed to "hold" the thigh bone in its correct position at the top of the slope have been developed through the years. These procedures included the use of large gauge sutures, stainless steel wire, and stripes of nearby tendons and ligaments. None of these procedures corrected the basic underlying problem.

Hip Dysplasia

Hip Dysplasia is a hereditary disease that affects the hip joints of dogs. Hip dysplasia is characterized by a looseness in the hip joint that causes abnormal wear and tear on the femoral head (the ball part of this ball and socket joint) and the acetabulum (the socket). The wear and tear leads to malformation of the ball and socket, and can lead to arthritis. Dogs predisposed to hip dysplasia, unlike children, are born with normal hip joints. Hip dysplasia can be seen in some dogs as young as five or six months of age. In other dogs, signs do not develop until after the dog matures. Hip pain is generated by the abnormal arthritic bones rubbing against each other. Arthritis will worsen with time unless surgical treatment is administered.

NORMAL HIP JOINT

DYSPLASTIC HIP JOINT

The onset of arthritis can be slow. In fact, sometimes the onset is so slow that you cannot recognize it. Early signs of hip pain in a dog include hopping like a rabbit with the rear legs when running, difficulty in rising from a sitting position, stiffness in the first few steps after lying down, and a reluctance to walk normal distances or play as hard or as long as normal dogs of the same age. Exercise causes these signs to become more prominent. It is important to remember that dogs do not usually cry when they are in pain. Instead, they demonstrate their pain by not properly using the joint or joints that hurt. As the arthritis becomes more severe, dogs will be reluctant to play or go on long walks. Some dogs may not want to walk at all if suffering from severe arthritic pain. Most dogs with hip dysplasia will have both hips affected. Because of this, your dog may not have an obvious limp in one leg because the arthritic pain is more or less equal in both hips.

Radiographs (x-rays) are used routinely to diagnose dogs with hip dysplasia. X-ray changes may be present prior to the onset of clinical signs. Some dogs go through life with no clinical signs but have severe changes seen on their radiographs. It is important to treat the patient and not the radiograph.

The primary treatment for hip dysplasia is surgery. Medical treatment and acupuncture can be used to alleviate arthritis pain, but these treatments do not correct the underlying cause of the hip pain.

Currently, there are three accepted surgical procedures for the treatment of hip dysplasia: Triple Pelvic Osteotomy (TPO), Femoral Head and Neck Excision (FHNE), and Total Hip Replacement (THR). Other procedures are available, but these have been found to be ineffective in the long run.

Triple pelvic osteotomy is typically performed in dogs less than twelve months old as an arthritis prevention surgery. This surgery must be performed before arthritis sets in and before the ball or socket is malformed. Dogs with arthritis already present, or dogs with abnormally formed femoral heads or acetabulums are not good candidates for this surgery. Since early detection is essential, x-rays should be taken at about six months of age in dogs with clinical signs consistent with hip dysplasia. Surgery involves rotating the socket so that the ball sits more deeply in it. If both hip joints need surgery, the procedures are staged; that is, one side is operated on first and then the other side is operated on later, usually in four to six weeks.

Femoral head and neck excision can be performed at any age and on both hips at the same time. This surgical procedure involves removing the ball part of the joint and positioning the body’s normal muscle tissue between the two bones. The body will also lay down scar tissue which helps form a false joint. This procedure is very effective at removing the pain associated with hip arthritis.

Total hip replacement is used primarily for larger dogs. This procedure is very similar to the procedure performed on people. The entire hip is replaced using high density polyethylene for the socket and a cobalt chrome alloy for the ball. This is an excellent procedure for both eliminating the pain associated with hip arthritis and restoring normal hip motion and function. The surgeons at SouthPaws have been performing this surgery for over 13 years with an overall success rate greater than 90 percent.

Once the proper surgical procedure is completed and the dog has recuperated, a full range of activities can resume.

Intervertebral Disc Disease

Intervertebral disc disease (IVD) can occur in all breeds of dogs, but it is most commonly seen in the chondrodystrophic breeds (these are the short leg, long back breeds, such as dachshunds, shih tzus, Lhasa apsos, beagles, and basset hounds). These breeds of dogs are susceptible to degeneration of their intervertebral discs at a young age. This degeneration weakens the disc, making it more susceptible to rupture. Clinical signs are related to the ruptured disc putting pressure on the spinal cord.

The back of a dog is made of a series of bones (the vertebrae). The intervertebral disc lies between each vertebrae. The spinal cord is located directly above the discs. The cord is surrounded on each side and on its top by bone. The normal disc is composed of a tough outer layer (the annulus fibrosus) and a gelatinous inner layer (the nucleus pulposus). The normal disc provides a cushioning function and imparts flexibility to the back.

The disc degeneration associated with IVD can start within the first year of life. The degeneration causes the nucleus pulposus to dehydrate (lose its water content) and to lose proteins. This together causes the disc to become less elastic and, in a sense, more brittle. The diseased disc is less able to withstand the forces put on the back during normal activity (such as running and jumping). If a force is placed on the diseased disc greater than that disc can withstand, the disc can rupture. When a disc ruptures, the top part of the annulus fibrosus (the part closest to the spinal cord) will tear and the nucleus pulposus is forced upwards. The rupturing disc hits the spinal cord, causing swelling and a disruption of the normal blood flow to the cord. This disrupts the function of the nerves traveling through the spinal cord. Clinical signs are related to how many nerves are affected. Clinical signs range from mild back pain only to complete paralysis of the hind legs. Surgery is the treatment of choice in dogs whose ruptured disc causes paralysis.

Surgical treatment for IVD disease is a step-wise process. Normally, neither the disc nor the spinal cord can be seen on regular x-rays. To determine if a disc has ruptured, and to identify which disc has ruptured, a myelogram must be performed. A myelogram involves the injection of a dye (which can be seen on an x-ray) into the space immediately surrounding the spinal cord. If a disc has ruptured, it will disrupt the normal filling of the dye in the area where the disc came out. Surgery is directed at the site of disc rupture.

Surgical treatment for IVD disease is a step-wise process. Normally, neither the disc nor the spinal cord can be seen on regular x-rays. To determine if a disc has ruptured, and to identify which disc has ruptured, an MRI or a CT-myelogram must be performed. A myelogram involves the injection of a dye (which can be seen on an x-ray) into the space immediately surrounding the spinal cord. If a disc has ruptured, it will disrupt the normal filling of the dye in the area where the disc came out. MRI does not require injection of a dye. CT-myelogram does. Surgery is directed at the site of disc rupture.

The prognosis for improvement after surgery varies from dog to dog and depends upon the severity of clinical signs. For dogs who have hind leg paralysis but who still have sensation in their legs, surgery done within 24 to 48 hours after onset carries about a 90 percent success rate. The length of time after treatment required to see the start of improvement varies from several days to four or five months. Most dogs will show some signs of improvement within several weeks after surgery. During this period - before the dog starts to regain function of its legs - it remains paralyzed and requires special home care.

Treatment for paralyzed dogs is usually straightforward, but can require some effort. It is much, much more difficult to maintain a paralyzed large breed dog (such as the typical 90 pound Doberman) than it is a dachshund. The dog will need to be confined to a small area, such as a playpen for small dogs, to keep it from dragging itself around with its front legs. The confined area should be well padded to help prevent pressure sores. The dog might also need to be turned from side to side several times daily to help prevent sores. A fairly large number of paralyzed dogs will lose bladder function in addition to losing hind leg function. Most of these dogs are unable to urinate. If this is the case, we have to express and empty their bladders for them (this is usually easily done by putting pressure on their bladder through their abdomen). Ideally, this is done several times per day. Return of bladder function varies widely also, but generally tends to improve at the same time that hind leg function improves. Finally, it is helpful to do some physical therapy on the paralyzed legs. The legs are flexed and extended to stimulate the muscles to keep them from getting too weak during the period of paralysis. Although there appears to be a lot of work to do to maintain a paralyzed dog, most people find that, once a routine is established, it is very manageable. It is also very rewarding in that the majority of dogs will regain use of their legs after surgery.

Veterinary Anesthesia

Veterinary medicine has become increasingly sophisticated over the years. Veterinary surgeons are performing many of the same procedures in animals that are performed in people. Accordingly, veterinary anesthesia has developed and advanced to meet the needs of the surgeon and the patient.

When a dog or cat comes to SouthPaws for a surgery, it is first given a complete physical examination by the veterinary nurse and the surgeon. The doctor will discuss the surgery with you and a time will be set up for the procedure to take place. In older animals (older than five years old), blood will be drawn before the day of surgery so that the patient’s body function can be assessed. Usually, a complete blood count (to check for anemia and changes in the white blood cell count) and a chemistry profile (to check for kidney and liver function) will be performed. This is important to do so that we can determine which is the best anesthetic drugs to use for the surgery. In younger animals, a simpler blood test will usually be run the day of surgery.

On the day of surgery, the animal is given a sedative shortly before its procedure to relax it. Some hair is clipped from its leg (usually a front leg) so that an intravenous (IV) catheter can be placed. The IV catheter allows us to administer anesthetic drugs to the patient and also allows us to give the animal intravenous fluids during and after the surgery.

The actual anesthetic procedure is a two step process. Drugs are initially given into the catheter to "induce" anesthesia. This will gently and quickly cause unconsciousness so that a breathing tube can be placed through the mouth and into the trachea (windpipe). There are a large number of induction anesthetic drugs available to us; we use the drug that is most appropriate for that particular animal. The tube is then hooked up to an anesthetic machine which allows us to administer a gas anesthetic. The gas anesthetics we use at SouthPaws are the safest drugs available for use in veterinary medicine. This gas anesthetic will "maintain" the animal under anesthesia throughout its surgical procedure. The animal’s surgery site is then prepared for surgery and the animal (along with its anesthetic machine) is moved into the operating room.

During the preparation of the animal before the surgery and all during the surgery, a number of pieces of equipment are used to allow us to monitor the patient’s condition. An electrocardiogram (ECG) is used to monitor the electrical activity in the patient’s heart. This helps us to make sure that the animal’s heart is not beating too quickly or too slowly and that there are no arrhythmias. A blood pressure monitor is used to measure the patient’s blood pressure. A pulse oximeter is used to let us make certain that there is enough oxygen in the patient’s blood. A machine is also used to measure the animal’s carbon dioxide level, so that we can make sure it is breathing well enough. Finally, our most important monitor is our anesthetic nurse, who watches over the whole animal and makes certain that everything is going all right.

Before, during and after surgery, patients are given medications to relieve any pain that might develop from the initial problem or from the surgery. We use a combination of oral, transdermal and injectable pain medications including constant rate infusions and epidurals. It is always one of our highest priorities to make certain that we provide as much pain relief as is necessary so that the animal is as comfortable as we can make it.

Ear Disease in Dogs and Cats

Dogs and, less frequently, cats are commonly affected by infections of the ear. Many times, the infection is caused by yeast or bacteria and is easily treated with medications, such as ear flushes and antibiotics. Some animals, though, are susceptible to repeated ear infections. Cocker spaniels are notoriously susceptible to repeated ear infections as are other breeds who are commonly affected by skin disorders.

The anatomy of a dog’s ear makes it more difficult to treat infections. The external ear of the human (the part of the ear that extends from the eardrum to the outside) is short, straight, and horizontal. This allows any fluid that might accumulate to drain straight out; it also makes it easy to get ear medication all the way to the eardrum. The dog’s ear is very different. The external ear of the dog is shaped more like a funnel, with one portion (the vertical ear canal) that goes straight up and down, and a smaller portion (the horizontal ear canal) that takes a 90 degree turn from the bottom of the vertical canal and courses to the eardrum. This anatomy makes it difficult for fluid in the ear to drain out (because it has to fight gravity and travel upwards through the vertical canal before it can get out) and makes it difficult to get medication all the way down to the ear drum.

Chronic otitis externa is the term that describes long standing or repeated infections of the external ear canal. It is associated with anatomical and physiological changes to the external ear. In the face of long standing infection, the skin that lines the ear becomes inflamed and thickened. This makes the horizontal and vertical canals even smaller which makes it even more difficult for infection fluid to drain. The inflammation triggers ear wax and inflammatory fluid production, which creates a substance in which bacteria thrive. The normally pliable cartilage that helps form the ear becomes calcified (in essence, it turns to bone) which also can interfere with drainage. Finally, the infection in the external ear can erode through the ear drum, spreading the infection to the middle ear.

Treatment of ear infections depends on the severity of the problem. Simple infections can usually be treated successfully medically. In cases where the infection does not respond to medical management, or in cases where the infection recurs, surgery might be necessary. There are two basic types of surgery for the treatment of ear disease. The first surgery is designed to alter the anatomy of the dog’s ear to make it more like the human ear. It involves either removing the entire vertical canal (called a Vertical Canal Ablation) or just the wall of the vertical canal (called a Lateral Wall Resection, or a Zepp Procedure). This will result in the horizontal canal opening directly to the outside (leaving a short, straight, horizontal canal, just like the human ear). This surgery needs to be performed early, before there are changes that cause the horizontal canal to be excessively narrowed. It is also sometimes combined with a procedure (called a Bulla Osteotomy) that opens and cleans the middle ear if there is extension of the external ear infection to the middle ear.

The second surgery is a more aggressive surgery. It is considered to be a salvage surgery that is done when no other treatment will work. This surgery is called a Total Ear Canal Ablation and involves removal of the entire ear canal (vertical and horizontal), the ear drum, and part of the middle ear. This surgery will permanently remove the infected ear canal and allows the middle ear to be drained. It is usually a very good procedure for permanently resolving long standing and painful ear infections. In theory, this surgery, if performed on both sides, will make the dog near deaf because it removes the whole sound amplification system of the ear. However, most dogs are near deaf anyway before this surgery because of the extent of their ear disease, and most owners report that their dog can still hear, although not quite as well as normal, even if both ears are operated. This procedure is preferred if there are tumors within the ear.

Most dogs respond quickly to surgical treatments for ear disease. The vertical canal ablation and lateral wall resection surgeries do sometimes require continued treatment of the ears, but the treatment is usually easier to perform and is needed less frequently. Many dogs do not require any treatment at all after these surgeries are performed and the active infection is brought under control. The key to successful vertical canal ablation and lateral wall resection is to perform the surgeries early, before a lot of damage has been caused to the ear by the infection. If the damage has reached a point where these two surgeries are not options, then total ear canal ablation is the treatment of choice.

Laryngeal Paralysis

Laryngeal paralysis is a relatively common disorder causing difficulty with breathing. It typically occurs in middle age and older, larger breed dogs, but it can be seen in small breed dogs and occasionally in cats. It can occasionally be seen as a congenital disease in young Bouvier dogs, Dalmatians, and Siberian huskies.

Laryngeal paralysis refers to paralysis of the muscles that open up the upper airway (specifically, these muscles pull the two vocal folds in the larynx apart from each other, thereby increasing the size of the opening into the trachea and lungs). Most of the time, the specific cause of the muscle paralysis is not known. Occasionally, laryngeal paralysis is only one sign of a systemic neurological disorder, but most of the time it is a problem that occurs by itself.

Clinical signs of laryngeal paralysis are related to failure of normal movement of the vocal folds. Since the vocal folds cannot be pulled apart from each other when breathing, the opening of the airway is smaller than usual. This means that the dog is not able to get as much air into his or her lungs as is needed. Common clinical signs include progressively noisier breathing, intolerance to exercise, and sometimes a voice change. More severe signs include coughing/gagging, vomiting, and sometimes a near inability to breathe. Laryngeal paralysis can be an emergency situation if the dog is unable to breathe.

Definitive treatment for laryngeal paralysis involves surgery. If a dog is in a crisis situation - where it cannot breathe and is essentially choking - emergency intervention is essential. A dog in this situation is typically sedated to decrease anxiety, and an endotracheal tube might be placed so that oxygen can be administered. Often, sedation is sufficient to calm the dog down enough to allow improved breathing.

There are several types of surgery available for laryngeal paralysis. All of them are designed to increase the size of the opening of the airway to allow easier passage of air. The most successful surgery, and the one most frequently performed, is called ARYTENOID LATERALIZATION, or laryngeal tieback. This surgery involves opening the larynx from the side of the neck to expose the piece of cartilage to which the vocal fold attaches. Typically, this is done on the left side of the neck. The cartilage is freed from its attachment and pulled back and to the side and sutured in this position. Doing this will pull the left vocal fold off to the side which increases the size of the opening to the airway. Only one vocal fold usually needs to be tied back. Most dogs respond very nicely to this surgery. The surgery does not necessarily make the dog perfectly normal and act like a puppy again, but it is very good at improving their ability to breathe and is excellent at preventing the breathing crises which can occur with laryngeal paralysis.

After the surgery, most dogs are sent home for a couple of weeks of rest. Mild coughing is common after the surgery, but should resolve within a week or two. Improved breathing is usually seen almost immediately after surgery and usually lasts for the life of the dog.

Brachial Plexus/Nerve Sheath Tumors

One of the more difficult diagnostic challenges you can face in veterinary practice is the brachial plexus/Nerve sheath tumor (PNST). These tumors are derived from the cells surrounding the axons of peripheral nerves. They have been known by a variety of names, including neurofibromas, neurofibrosarcomas, and schwannomas, but are now referred to as PNST due to their presumed common cell of origin (the Schwann cell).

What makes PNSTs so much of a diagnostic challenge is the similarity of their presenting clinical signs to many other, more common, orthopaedic disorders. The most common clinical sign associated with PNST is chronic, progressive, unilateral forelimb lameness. In a 1995 study of 51 cases of PNST, 78.4% of dogs presented with this sign. This tumor is typically seen in older dogs (average age was 8.7 years), but has been seen in dogs as young as 3 years. Because this tumor is usually seen in older dogs, it is very common to misinterpret it as elbow or shoulder arthritis, two conditions also commonly seen in older dogs. Pain on palpation near the tumor site was seen in 48.7% of dogs. Since most of these tumors grown in the axillary region, it is again common to mistake the pain as derived from the shoulder. Only 37% of dogs had a palpable mass (these are typically found only on deep palpation of the axillary region, which sometimes requires sedation for efficient palpation). One sign that is commonly seen with PNST and less commonly seen with chronic arthritis is muscle atrophy. About 93% of dogs with PNST had moderate to severe muscle atrophy of the affected limb.

Diagnosis of PNST often requires multiple tools. The first step is to take radiographs to look for obvious orthopaedic abnormalities, such as fractures or bone tumors. If the radiographs do not fit the clinical picture, we recommend electromyography (EMG). In the 1995 study, 100% of cases in which an EMG was performed demonstrated abnormal, spontaneous electrical activity, indicative of neurological compromise to the muscles of the affected limb. Electromyography is not specific for PNST, but is is a sensitive test to help differentiate between denervation and disuse muscle atrophy (usually associated with neurological and orthopaedic causes of lameness, respectively). If an EMG is abnormal, additional tests are necessary to help better define the nature and scope of the probably tumor. Myelography can be very useful to identify extension of the tumor into the spinal canal At SouthPaws, we have been utilizing MR imaging more frequently when dealing with PNST. This test costs about the same as a myelogram, and has been very good at demonstrating both intra-spinal extension of PNSTs as well as better defining the peripheral limits of the tumor. We have been very excited about the results from MR scans and about the benefits they provide when planning the surgical approaches used to resect the tumor. The best hope we have to successfully treat PNSTs is early, accurate diagnosis, which electromyography and magnetic resonance imaging can assist in providing. Both electromyography and magnetic resonance imaging (as well as myelography) are available through the SouthPaws neurology service.

SouthPaws has an active and interactive oncology unit, combining medical, radiation, integrative, and surgical oncology services, which allows a multi-disciplinary approach to the cancer patient. It is very common to have many of the services at SouthPaws participate in the diagnosis and treatment of our cancer patients. We view this approach as vital to providing the best care possible. Our goal has always been to provide our cancer patients - as well as all of our other patients - with as long and good a quality of life as can be achieved. SouthPaws has a strong and experienced oncology team; we are, as always, ready and willing to help referring veterinarians and their patients in any way we can.

The Omentum - The Surgeon's Friend

The omentum has been described in the literature as both "abdominal policeman" and "the forgotten organ." It is a unique and versatile organ that can be utilized for a variety of surgical procedures. Given this, the omentum can also be described as "the surgeon’s friend."

The omentum is rich in lymphatics and is a source of blood vessels and fibroblasts. It is thin, so it provides very little structural support, but it can be utilized to cover other organs and to obliterate space. The omentum is attached to the stomach and is composed of two leaves. The blood supply is derived primarily from the stomach vessels. Because of this arrangement, the omentum can be extended in length. The blood supply to one leaf is ligated, and this leaf is freed from its attachment and folded caudally to increase the total length of the omentum. Also, a flap can be created from this extended omentum to further increase its total length. These modifications increase the total length of the omentum to the point where it can reach any point in the cat and nearly any point in the dog. This allows the omentum to be utilized in a large number of surgeries involving all or nearly all of the animal’s body.

The most common use of the omentum is as an adjunct to intestinal surgery. The omentum is either wrapped around or sutured to the intestine at an anastomosis or enterotomy site. The omentum fills in small gaps between sutures in the intestine, and provides another source of blood vessels and inflammatory cells for healing. The omentum should not be considered, though, as a replacement for good suturing technique nor will it bring about viability in a nonviable segment of intestine. The omentum has also been used similarly in thoracic esophageal surgery when an aid to healing is desired (the omentum is brought through a small hole that is created in the diaphragm and placed or sutured around the esophageal surgery site).

The omentum can also be used to assist healing in other sites. Chronic, non-healing skin wounds can be assisted by omentalization. The omentum is harvested from the abdomen and, in most cases, lengthening techniques are used to create a flap that will reach the wound site. The omentum is tunneled under the skin to the wound site, and sutured into place. The supplemental healing properties that the omentum provides has been shown to dramatically enhance wound healing. Many chronic wounds that have had multiple surgeries and/or a prolonged period of local wound care without success have gone on to heal dramatically after omentalization.

Finally, the omentum can be used as a physiological drain. The rich lymphatic and blood vascular supply within the omentum can assist in the absorption of fluids in a number of body locations. This method can be used to eliminate the need for drains that exit the skin to drain to the outside of the body. Two relatively recently described techniques that utilize the omentum as a physiological drain are treatments for prostatic abscesses and for prostatic or paraprostatic cysts. The previously described treatment methods for prostatic abscesses were to place one or multiple Penrose drains into the abscess cavity and to exit them through the skin lateral to the prepuce. This location made bandaging difficult or impossible, so there was frequently extensive drainage that was inconvenient for the dog and owners; also, ascending infections were a potential concern. With omentalization, the prostatic abscess cavities are digitally broken down to create one cavity. The omentum is extended if needed, passed through the hole in the prostatic wall (that was made when the single cavity was created), and then out through the second hole, or it is passed around the prostatic urethra and exited out through the first hole. The omentum is sutured in place. The body wall is closed routinely, with no drains emerging through the skin. This technique effectively treated prostatic abscesses most of the time and was associated both with lower complication and lower recurrence rates. Prostatic cysts are treated similarly, with similarly good results.

The omentum is an extremely useful organ with a variety of potential uses. Clearly, it was placed in the abdomen for a reason. The best rule of thumb, then, is to go ahead and utilize it when you can.

PennHIP TECHNIQUE TO BE USED AT SOUTHPAWS FOR EARLY DETECTION OF HIP DYSPLASIA

Hip dysplasia is a common heritable orthopaedic disease primarily affecting large breed dogs. The disease causes pain and can adversely affect the quality of the affected dog's performance and life. There is no treatment for the disease apart from corrective or salvage procedures. The main approach towards the elimination of the disease has been through selective breeding. The Orthopedic Foundation for Animals has established a set of radiographic guidelines to help identify dogs with hip dysplasia so that affected animals could be removed from the breeding pool of dogs. Despite years of genetic manipulation based on OFA guidelines, hip dysplasia remains a prevalent condition. This may, in part, be related to the limitations of the OFA system of hip evaluation: dogs will not be certified as hip dysplasia-free until two years of age, a time by which many nonprofessional breeders have already bred their dogs, and the hip extended view used in the OFA method tends to under represent the amount of hip laxity present.

Because of these limitations, a new radiographic method - the PennHIP method - has been developed to try to better assess the susceptibility of a dog to developing signs associated with hip dysplasia at an age more practical for breeding considerations.

The PennHIP method involves the direct measurement of the amount of hip laxity present in a dog. Hip laxity has been shown to be the major factor predicting a dog's susceptibility for developing hip dysplasia. From the measurement of the amount of hip laxity present, the dog can be categorized as to the likelihood of it developing hip dysplasia. The method is purely objective (no subjective component involved), is repeatable, is comparable from one dog to another and from one breed to another, and can be done with good accuracy in dogs as young as six months of age. The procedure involves a short acting reversible anesthetic followed by distraction radiographs to determine hip laxity. The dog's susceptibility to developing hip dysplasia is determined based on the amount of hip distraction present and standards established for the particular breed of dog being evaluated. This allows the veterinarian and owner to make an informed decision about the suitability of using that animal in any breeding program.

The PennHIP method of evaluating hip laxity is currently limited to selected veterinary centers whose veterinarians have been trained in the method and are equipped with the instrumentation necessary for the procedure. Dr Dan Brehm has complete the certification requirements and is currently performing PennHIP radiographic evaluations. If you have clients that may be interested in this procedure, or if you wish to learn more, please contact Dr. Brehm.

Canine Soft Tissue Sarcomas

These tumors are cancers of connective tissue. They include fibrosarcomas, chondrosarcomas, myxosarcomas, undifferentiated sarcomas, liposarcomas, malignant fibrous histiocytomas, hemangiopericytomas, peripheral nerve sheath tumors, rhabdomyosarcomas, leiomyosarcomas, neurofibrosarcomas, and several others. This class of cancers can be talked of as a group as their behavior is quite similar. This group DOES NOT include hemangiosarcoma, osteosarcoma, synovial cell sarcoma, and histiocytic sarcomas as these cancers have different and unique behavior patterns for each type of cancer.

Soft tissue sarcomas (STSa) in dogs are locally invasive cancers. They are never confined by a "capsule". They can originate in any portion of the body (skin, subcutis, muscle of the head, neck, trunk, flanks, legs, hips, etc.) as well as within body cavities and internal organs.

The behavior of a STSa can be predicted based upon two factors: grade and margins of surgical excision. In order to determine grade, a large section biopsy (incisional or excisional) must be performed. Low/intermediate grade STSa have between a 10 and 20% chance of metastasizing from the primary tumor site to the lungs (predominantly). High grade STSa have a 50-70% chance of metastasis.

Surgical excision of STSa tends to be the primary form of therapy. Careful planning (sometimes requiring advanced imaging) before surgery gives us the best chance of removing the entire STSa. Two centimeter margins in an en bloc excision pattern is the usual goal for the surgeon. This approach means that the surgeon’s blade is an inch away from the known edge of the tumor. This incision is deepened to include underlying muscle, or other tough connective tissues, at least an inch below the known deep extent of the tumor to remove a block of tissue surrounding the STSa. The surgeon attempting a local cure on this type of cancer should never "shell out" this type of tumor, or cut it out with narrow margins, then go back and try to take more tissue during the same procedure. Margins of this "block" of normal tissue surrounding the cancer are inked, and the entire block submitted for histopathology. The pathologist then examines cut sections and tells us whether the margins are clear of cancer cells and by what distance. If a true "clean margin" has been obtained, the chance of local recurrence is less than 5%.

If a "clean margin" and low/intermediate grade STSa has been diagnosed (post-surgical excision), then no additional local or systemic therapy may be necessary as the chance for local recurrence is under 5%, and the chance for systemic metastatic disease is under 20%.

If a low/intermediate grade STSa has been diagnosed, but margins were NOT clean, we have the following treatment options:

1. Repeat surgery with wider margins.
2. Full course radiation therapy to the incision to include these wide margins. This treatment has an 80% chance of preventing local recurrence.
3. Watchful waiting – just as soon as any evidence of local recurrence happens, we get aggressive surgically at that time, assuming overall state of health and repeat staging testing shows no evidence of spreading cancer.
4. Drug therapies are available that MAY slow the chance of local recurrence.
5. Intralesional chemotherapy to the incision site within 1-2 months of surgery MAY slow or prevent local recurrence.

If a high grade STSa has been diagnosed, systemic chemotherapy is often used after surgery to try to maximize quality and quantity of life. Remember, since 50-70% of these tumors metastasize to the lungs or other organs, it is rare for dogs with this type of STSa to live for more than 6-8 months without successful chemotherapy. Doxorubicin-based chemotherapy protocols are the most commonly used and have good response rates (most responding dogs do not develop metastatic disease for 1-2 years).

Transitional Cell Carcinoma

Transitional cell carcinoma (TCC) is the most common tumor of the bladder and urethra in dogs and cats. It develops within the "inside lining" cells of these tissues. In some male dogs, TCC can also develop within the prostate and occasionally within a kidney.

TCC is a cancer that is locally invasive causing irritation, bleeding into the urine, straining to urinate, straining to defecate, frequent urination, urinary incontinence, or urethral or ureteral obstruction. Urethral obstruction is a life threatening emergency as the bladder cannot be emptied and bladder rupture or death can occur. Ureteral obstruction will cause urine to back up into one or both kidneys resulting in hydronephrosis and eventual kidney failure.

TCC is also a "spreading" cancer in that it implants itself throughout the lower urinary tract so it is nearly never confined to the one "tumor mass" that is initially found, and in 50-70% of patients, it also metastasizes through the bloodstream or lymphatics to the local lymph nodes, lungs, bones, or other organs.

Without successful therapy, this cancer will usually cause worsening signs of frequent urination, painful or difficult urination, bloody urine, incontinence, loss of appetite, vomiting, weight loss, cough, difficulty defecating or bone pain/lameness within 1-2 months (dependent upon the initial tumor size and location).

Surgery is never curative for this type of cancer. If a mass is able to be removed from the bladder, both the implants as well as the metastatic disease will eventually become deadly.

Chemotherapy (mitoxantrone, carboplatin, doxorubicin, and others) is commonly used in combination with an oral anti-inflammatory drug called piroxicam. This combination of medications has 30-50% response rates for 8-12 months (on average). These chemotherapy drugs are given as outpatient IV therapies once every three weeks for a total of 4-5 doses depending on response to therapy (typically judged via examination and ultrasound). Side effects of these chemotherapy drugs used for this cancer are uncommon ( < 10% of dogs/cats) but can include a transiently low white cell count, platelet count, or gastroenteritis.

Piroxicam alone has a 20% response rate for typically 3-6 months. Piroxicam is an aspirin-like drug and cannot be given in combination with any other over-the-counter or prescription anti-inflammatory, pain medication, prednisone / steroid, or arthritis medications without checking with us FIRST. Side effects include stomach ulcers, and rarely, worsening of already-present kidney disease. Bloodwork should be monitored every 8-12 weeks in dogs or cats taking this medication.

Side effects of Chemotherapy

In general, most animals receiving chemotherapy experience no side effects. If their cancer is going into remission, most have more energy and an improved appetite. As our goal in treatment is a “normal quality of life at home”, we need you to tell us if your pet’s week after chemotherapy is anything other than normal!

Inappetence, nausea, vomiting, and diarrhea are rare side effects which might be seen in sensitive individuals. If GI symptoms occur, do not feed your pet for 12-24 hours. Pepto-Bismol may be administered to dogs. Dosage is one tablet per 20 pounds three times daily. Do Not give Pepto-Bismol to a cat. Cats should receive Pepcid/famotidine 10mg tablets, ½ tablet once a day. If the condition lasts longer than 24 hours, please call the Oncology service. When the condition resolves, start feeding bland foods (rice and boiled hamburger, boiled chicken and noodles) in small amounts frequently. Even if symptoms resolve quickly, do tell us if these signs of GI upset occurred in your pet – and when they occurred following chemotherapy -- prior to the next treatment. Depending upon the timing, we may be able to use prophylactic/preventative medications the next time that chemotherapy is administered in your pet. If your pet is unable to drink water without vomiting, call us immediately as fluid support may be necessary.

Fever in a patient receiving chemotherapy is always a concern. (Normal rectal temperature is between 101-102 degrees.) If your pet has a fever, please call SouthPaws immediately. Depending upon the timing of the fever after chemotherapy, your pet might have a low white blood cell count, and we may recommend an immediate CBC and antibiotic therapy.

Hair regrowth of a shaved area can be prolonged and excessive shedding may be induced in some breeds of dogs by certain types of chemotherapy. Sometimes the skin can become darker and thicker. The hair coat usually returns to normal after chemotherapy has been completed.

Pets receiving chemotherapy should be able to perform and enjoy all of their normal activities. If you notice a decreased ability to exercise or any other problem, please let us know during your next visit.

Chemotherapy drugs and their metabolites can be excreted from your pets’ body for up to 48 hours after the treatment. For your protection, wear gloves and wash your hands after handling your pets’ urine, feces, and vomitus during this period of time.

If you have any problems or questions, please do not hesitate to call us at Southpaws (7803) 752-9103 Monday through Friday 8 a.m. to 6 p.m., or anytime at 703-752-9100.

Mast Cell Tumors in Dogs

Mast cell tumors (MCT) in dogs are classified into three grades: I, II, and III. Both I and II are considered low grade and grade III is considered a high grade process. Grades are determined by biopsies taken of the tumor during surgical removal.

Low grade mast cell tumors generally have a less than 15% chance of metastasis. Aggressive local therapy is the treatment of choice for these tumors. A local cure can be achieved when a surgeon removes the tumor with "clean" surgical margins. There is a 95% cure rate if radiation is used in the area after surgical removal if the surgical margins are not clean. Chemotherapy is only indicated if there is a MCT in an anatomically difficult area for surgery or radiation therapy, if the pet has had previous multiple MCTs, or if there are negative prognostic factors (location, metastasis, rapid growth).

High grade MCTs have a 90% chance of metastasis with the average survival time being 3 - 4 months without successful treatment. This type of MCT metastasizes to the lymph nodes, liver, spleen, and bone marrow.

There are several treatment options for patients with grade III mast cell tumors.

1. Prednisone therapy. Giving prednisone by mouth at home provides a short lived response in 20% of patients.
2. Vinblastine/Prednisone therapy. This chemotherapy protocol utilizes a drug called vinblastine that is given IV weekly for 4 doses, then every other week for 4 doses. Prednisone is given at home by the owner.
3. Vinblastine/CCNU/ Prednisone therapy. This protocol alternates IV vinblastine with oral CCNU given at the clinic every 2 weeks for 8 total treatments (4 treatments of each drug) Prednisone is given at home by the owner.

With either treatment option 2 or 3, 60% response rates are described for up to 1 - 1 1/2 years.

A common side-effect of MCT in dogs is gastric ulcer disease. The best preventative for MCT-induced ulcers is Pepcid (famotidine). Signs that ulcers are occurring include vomiting (with coffee ground-looking vomitus) and black tarry stools. Signs that the mast cell tumors are progressing are inappetance, weakness, collapse, and masses enlarging (causing swelling, pain, and bleeding).

Chemotherapy should be started as soon as possible after diagnosis of a grade III mast cell tumor to increase the effectiveness of the therapy. For some grade III mast cell tumors, radiation therapy may also be recommended.

Lymphoma in Dogs - Relapse/Rescue

Unfortunately, we know that dogs with lymphoma will almost certainly relapse. When relapse occurs, there are several "rescue" protocols than can be used to treat them. These protocols use different chemotherapy drugs than the induction protocols because the cancer has become resistant to the drugs previously given.

These are some of the "rescue" protocols we offer:

1. CCNU: This pill requires visits to SouthPaws every 3 weeks for as long as the treatment works. CCNU has a 20% chance of causing a very low white blood cell count 7 – 9 days after the treatment. Liver toxicity is a rare side effect that requires monitoring of liver enzymes so that therapy can be adjusted if sensitivity is developing. Other side effects are extremely unlikely.
2. DMAC: This therapy requires an IV injection of actinomycin D (Cosmegen) every other week and two medications (dexamethasone and alkeran) to be given at home in the off week. The protocol requires visits to SouthPaws every other week for 2 months, then every 3 -4 week visits. Side effects are uncommon with this protocol (less than a 10% chance of skin reactions to the injection, low white blood cell counts, or nausea).
3. Mitoxantrone: This IV injection is given every 3 weeks for 4 treatments, then every 6 weeks thereafter until it is ineffective. There is a less than 5% chance of low white blood cell counts as a side effect of this treatment.
4. Doxorubicin/DTIC: This combination is an infusion that takes about 8 hours to administer safely. Side effects can occur in up to 20% of dogs and include low white blood cell counts, nausea, or loss of appetite. Medications are used in hospital during the infusion and sent home with you to try to prevent these side effects. This combination therapy is given once every 3 weeks.
5. MOPP: This therapy is given as 45 minute weekly infusions for two weeks in a row, followed by two weeks off. Medications will be used at home as part of this protocol. Side effects can include low white blood cell counts, nausea, and/or vomiting.
6. L-asparaginase: This therapy is given as a subcutaneous injection typically weekly for three doses then once every 2-6 weeks depending upon the patient. Allergic/anaphylactic reactions are possible in patients receiving multiple doses of this drug. Side effects (including anaphylaxis) are extremely rare with this drug, however.
7. Vinblastine/cytosine arabinoside: this protocol involves an alternating weekly IV treatment. Side effects could include low white cell counts, but are quite uncommon.
8. Additional combinations. Depending upon responses to prior therapy, we can sometimes combine therapies for better effect.

There is not a "best" rescue protocol. If one does not work, or when one fails, we can try one of the other protocols. Each subsequent remission time gets shorter, and less likely to occur as the cancer gets "smarter".

Please consider the treatment options listed and let us know how we can help with your pet’s ongoing care.

Lymphoma in Dogs

Lymphoma is defined as a cancer that affects the lymphatic system, including but not limited to the lymph nodes, spleen, liver, and bone marrow. Enlarged painless lymph nodes are a very common sign of lymphoma. Many people will also see non-specific signs indicating that their pet is not feeling well. Poor appetite, weight loss, and gastrointestinal upset are just a few examples.

To diagnose lymphoma, a fine needle aspirate can be used to obtain a sample of the cells at the questionable area, or a biopsy can be done. A biopsy will determine the grade of the cancer, a helpful piece of information. Other tests can be done to determine the stage of the lymphoma, but complete staging is not necessary in all patients. If more extensive staging is used to determine the extent of the disease, some of the diagnostic tools used may include radiographs, ultrasound, organ aspirates, and bone marrow aspirates.

The expected lifespan of a dog diagnosed with lymphoma without successful therapy is 1 - 3 months. With successful therapy, we can lengthen the survival by 10 - 16 months depending upon the anatomic form of the lymphoma and pet’s initial status.

We treat lymphoma with the most aggressive therapy that is appropriate for both the pet and its owner. We offer 4 standard treatment options.

1. Prednisone alone. With this therapy, an oral medication, prednisone, is given by the owner at home in order to make the pet feel better for 1 - 2 months. This treatment does not result in durable remissions and does not lengthen survival times.
2. COP protocol. This is a 3 drug protocol that uses two pill medications at home, and weekly vincristine injections at the hospital for 8 weeks. Once the 8 weeks are completed, we change to pills given at home and monthly vincristine injections (the maintenance phase). This treatment is the least expensive of the combination chemotherapy protocols.
3. Short CHOP plus maintenance. This 4 drug protocol involves weekly treatments for 12 weeks, using vincristine, cyclophospamide, prednisone and doxorubicin. Once the induction phase is completed (the first 12 weeks), we change to pills at home with monthly vincristine treatments.
4. 19 week combination protocol. This is a 4 drug protocol that involves weekly chemotherapy treatments (with prednisone, vincristine, cyclophosphamide, and doxorubicin) for 16 weeks. There are several "rest" weeks throughout the protocol.

No matter which protocol is used to treat lymphoma, we know that dogs will almost certainly relapse. When relapse occurs, there are several "rescue" protocols that can be used. These protocols use different chemotherapy drugs because the cancer has become resistant to the drugs previously given. The effectiveness of a rescue protocol is usually less than that of the initial treatment. Signs of relapse and/or end stage disease include enlarged lymph nodes, difficulty breathing, lethargy, inappetance, and fever.

Lymphoma is a disease that responds well to chemotherapy, but treatment is more effective if treatment is started soon after diagnosis. Our staff will guide you through the process of setting up treatment days to help accommodate your schedule and your pet’s needs.

Hemangiosarcoma

Hemangiosarcoma is a malignant cancer that forms in the internal lining of blood vessels. These cancers are common in dogs and rare in cats.There are three categories of hemangiosarcoma : internal(spleen, liver, other abdominal organs or heart); subcutaneous or intramuscular; and cutaneous.

Internal hemangiosarcoma can be found in the spleen, liver,heart, root of the mesentery, kidney, retroperitoneal space and occasionally in other organs. Initial diagnosis of this cancer is often made when the patient has a collapsing or weakness event triggered by internal bleeding from the tumor. The diagnosis can be suspected based upon ultrasonagraphic imaging and bloodwork, but definitive diagnosis requires excisional (surgical) biopsy of the mass. While surgery to remove these bleeding tumors is life-saving, unfortunately most dogs will live only 2-8 weeks following surgery due to the presence of rapidly-growing metastases.. We recommend chemotherapy following surgery for dogs with internal hemangiosarcoma, as with successful chemotherapy, life expectancy of these dogs increases to 6 – 8 months. With additional anti-angiogenic/metronomic therapy, we see 10-20% of dogs treated with surgery, chemotherapy and daily life-long therapy living for more than 12 months.

Dogs that are diagnosed with subcutaneous or intramuscular hemangiosarcoma should have the tumor completely excised by a surgeon. With surgery alone, the life expectancy of these patients is 6 months. We can increase this to 1 1/2 years or more with successful chemotherapy followed by anti-angiogenic/metronomic therapy.

Cutaneous hemangiosarcoma is a sun-induced cancer that does not invade the subcutaneous space. It is cured with complete surgical excision. It is advised that chest radiographs and abdominal ultrasound are performed to determine whether this disease is a primary tumor or a manifestation of metastatic disease due to an internal hemangiosarcoma, however.

Drop off Patient Policy

Chemotherapy patients are dropped off at our clinic Monday - Friday between 7 and 9 a.m. A detailed consent form is provided at each drop off so that you can inform us of any problems, concerns, or questions that you may have. Patients are admitted, and necessary blood samples or imaging studies requested by the oncology nursing staff. The oncologist will review all lab and imaging results, your written notes, and then perform a physical examination on your pet. If there are any concerns or changes needed, either the doctor or one of the oncology staff will call you prior to administration of chemotherapy. The nursing staff then performs the chemotherapy treatment and will contact you when your pet is ready to go home. NO PATIENT WILL BE TREATED WITH CHEMOTHERAPY UNTIL THE DOCTOR’S EXAMINATION IS COMPLETED. Doctors typically start these examinations between 8am and 10am. Chemotherapy patients will usually be ready for pick-up by 3-5 pm (unless that individual’s drug protocol requires a longer stay). Patients receiving doxorubicin treatments are typically treated last to ensure that several nurses are available to assist in this more complicated treatment. There are often between 15-20 chemotherapy patients dropped off daily – plus scheduled radiation therapy, I-131 therapy, and initial/recheck appointment patients to see.

If you prefer face-to-face appointments, you may schedule a recheck appointment for many chemotherapy treatments – as long as the actual chemo-treatment time is less than 20 minutes.

If you prefer to drop-off, but wait with your pet, you may do so and our oncology nursing staff will make every effort to let you know your likely wait time – but waiting with your pet will not ensure a shorter “drop off day” experience.

Canine Osteosarcoma

Your dog has a bone tumor. Most bone tumors in dogs are osteosarcomas and this handout describes osteosarcoma treatment options. We cannot cure this cancer, but we can control it for some time. Treatment is directed at removing the primary tumor and the pain associated with it, AND at slowing and preventing the occurrence of metastatic disease.

The options for treating the primary tumor are:

1. Amputation - with amputation alone, most dogs have a very comfortable life for 4-5 months.
2. Limb sparing surgery - this surgery is as effective as amputation for local disease control, but it is more expensive. Only some bone tumors (based on location and radiographic appearance) can have limb-sparing surgery.
3. Palliative radiation therapy - this treatment will never treat nor control the tumor, but will help with pain control. Radiation therapy typically involves 1-4 doses of radiation several weeks to months.

The options for metastatic tumor control include:

1. Cisplatin alone - The median survival time with this treatment is 12 months with 10% of dogs alive 2 years after starting treatment. Cisplatin treatment takes an entire day to administer, but side effects occur in only 10 - 15% of dogs. This treatment is given once every 3 weeks for 4 doses.
2. Carboplatin alone - This treatment is as effective as the first option, but side effects are very rare with this treatment plan. Carboplatin is given every 3 weeks for 4 - 5 treatments, with an average survival time of about 10 - 12 months.
3. Alternating carboplatin and doxorubicin – We give 3 carboplatin treatments and 3 doxorubicin treatments in an alternating 3/2 week pattern. Survival times in small studies are similar to carboplatin alone.
4. Doxorubicin alone - This option gives an average survival time approaching 12 months. The treatment is given every 2 weeks for 5 treatments and an echocardiogram would be necessary before the first and fourth treatment. Some gastrointestinal side-effects can be associated with this treatment. Chemotherapy without primary tumor control is not helpful.

Alternative treatments:

1. Pamidronate - a "bone hardening" drug given intravenously, is showing some promise in experimental studies as a pain controlling/fracture preventing drug; and also as an adjuvant to chemotherapy and/or radiation.
2. Triple pain therapy - with an anti-inflammatory, narcotic and neurologic pain blocker all given by mouth at home can improve comfort for several months. Watch for pain, fracture, lethargy and cough as signs of tumor progression

Once you decide which primary control measure and metastatic therapy are best for you and your dog, please contact our office so that we may schedule a first treatment. If surgery is needed, we can assist in scheduling an appointment with the SouthPaws surgery department.