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should be taken if a patient receiving gentamicin is undergoing surgery to assure that adequate blood pressure is maintained under anesthesia.  Once daily dosing of gentamicin (6 mg/kg in dogs) is less nephrotoxic than previously recommended TID dosing.  I have seen articles about the use of paromomycin to treat cats with various protozoal infections caused by giardia, cryptosporidium and pentatrichomonas.  Some articles fail to mention its potential nephrotoxicity, which has been well documented.

Lyme nephritis is sadly seen too commonly at SouthPaws, especially in Labrador and Golden Retrievers and almost certainly does not respond to any therapy.  These dogs have an acute onset of clinical signs with azotemia, protein losing nephropathy and edema with or without joint pain.  I have noted that they are often anemic (hematocrit in the 20s-30s), despite the relatively short clinical course, and are profoundly hypertensive. 

We definitely see some leptospirosis at SouthPaws, but far less than in New York where I did my residency (Ithaca seemed to have a nice little grippotyphosa infestation, ensuring that each student got to experience this disease!).  I consider leptospirosis as a possibility in every case of ARF (especially if there is concurrent liver disease) because I have seen it in all types of dogs, even little lap dogs - the type that you'd imagine would never touch the ground!  Use of the vaccine against serovars canicola and icterohaemorrhagiae has reduced the number of cases of leptospirosis in the U.S. so we mainly see infection with other serovars.  Based on the records of the patients referred to me, I don't think that many veterinarians are using the Fort Dodge vaccine against grippotyphosa and pomona yet so it is too early to tell whether this vaccine will reduce the incidence of leptospirosis in dogs.  Many dogs can be treated successfully with aggressive IV fluid therapy, ampicillin (and later amoxicillin - total of 14 days; followed by 14 days of doxycycline) and supportive care.  Others succumb to hematologic complications such as DIC or thromboembolic disease or develop anuria.

Ischemic injury to the kidneys is sometimes iatrogenic. When ACE inhibitors are used the BUN and creatinine should be monitored 1 week after starting therapy and then periodically to ensure that renal damage is not occurring. An overdose of a nonsteroidal anti-inflammatory drug (NSAID) or the combination of such a drug with a hypotensive episode can result in renal failure.  As mentioned above, care must be taken when anesthetizing our patients so that the systemic blood pressure remains adequate (mean BP > 60 mm Hg, or approximately systolic BP >100 mm Hg) for renal perfusion.

Diagnosis of ARF is based on a history of acute onset of clinical signs and azotemia with inappropriate urine s.g. (<1.030 in dogs, <1.035 in cats).  Remember that it is important to obtain a urine sample prior to fluid therapy.  Urine sediment may be "active" i.e. casts, bacteria, WBC, RBC and may contain protein and glucose.  Acidosis may be present.  An important differential diag

nosis is hypoadrenocorticism.  Remember that in ARF hyponatremia may be present due to vomiting and hyperkalemia may be present due to reduced urinary excretion and acidosis, so the presence of a Na:K < 27 alone is not diagnostic for hypoadrenocorticism.  An ACTH stimulation test is easy and safe to perform in these patients. 

Commonly I see animals with an acute exacerbation of a chronic renal disease, but these cases can usually be differentiated by a more chronic history of PU/PD, weight loss, the presence of anemia and perhaps a history of azotemia detected on previously performed blood tests (e.g. pre-operative screening).  It is important to recognize these patients so that we can alert the owners that while azotemia may be partially correctible with fluid therapy, renal disease will definitely persist.

Treatment involves IV fluid therapy, correction of electrolyte abnormalities and acid-base disturbances and treatment of the underlying cause (e.g. antibiotics for infectious causes; induction of emesis and administration of antidotes for toxic causes).  Gastroprotectants are given (I like famotidine 0.5 mg/kg IV q 12 hr, or PO q 24 hr) with or without sucralfate (0.25-1 gram q 6-8 hours depending on the size of the patient - cat/toy dog 0.25 g/dose, small/medium dog 0.5 g/dose, large dog 1 g/dose).  Sucralfate also has the added benefit of containing aluminum so it also acts a phosphate binder.  If renal failure is severe you should consider dose reductions of renally excreted drugs based on the patient's GFR.  However, since GFR is not able to be easily measured, I use the serum creatinine as a "rough" guide.  The initial dose of a medication is given at the usual dose ("loading dose"), then for future doses either the frequency of administration or the dose of the drug is reduced.  For example, if a dog had a creatinine of 4 mg/dl and the reference range was 0.5 to 2 mg/dl, after a loading dose I would give famotidine 0.5 mg/kg IV q 24 hr instead of q 12 hr, and give half of the dose of ampicillin (5 mg/lb instead for 10 mg/lb) q 8 hr (or alternatively give 10 mg/lb q 16 hours IV). As the serum creatinine improves, I increase the dose of the medication.

Monitoring of fluid input and output is extremely important. Body weight, central venous pressure (CVP), systemic blood pressure and skin turgor should be monitored.  Careful attention needs to be paid to urine output - where possible an indwelling urinary catheter with closed collection system should be placed so that if urine output falls below the minimum desired (1-2 ml/kg/hour) steps can be taken to prevent anuric renal failure.  If inadequate urine is produced my first step is to ensure that the patient is not volume depleted (CVPs are probably the best way to determine this) - if in doubt I usually give crystalloids at 3-5% of the body weight IV over 1 hour.  If this is ineffective I give furosemide (2-4 mg/kg IV, if effective continued at 1-2 mg/kg q 6-8 hours) and also start a dopamine CRI (1-5 ug/kg/min) as these medications work synergistically.  I have also used mannitol (0.5-1 gram/kg IV over 15-30 minutes, repeated q 4-6 hours if effective) if the other therapies have not been successful.  Dialysis (peritoneal or hemodialysis) is required if the above therapies are unsuccessful after 4-6 hours.  SouthPaws does not have hemodi

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