Glucagon Infusions

Dogs with profound hypoglycemia due to insulin overdose, insulinoma, and other abdominal tumors are frequently refractory to dextrose administration. The seizures may stop with a 2.5%, 5% or even 10% dextrose infusion, but often the blood glucose cannot be normalized. Prolonged hypoglycemia can lead to cerebral injury. In dogs with insulinomas, it often seems that the more dextrose that we administrator intravenously, the more refractory the hypoglycemia becomes, because the tumor releases additional insulin. Glucagon is the physiological antagonist to insulin. It can be used as a constant rate infusion to normalize blood glucose values - often without the need for an additional dextrose infusion. Getting an insulinoma patient off dextrose, and with a normal blood glucose makes diagnostics and surgical intervention much easier and safer for the patient. When owners opt to treat the non-resectable or metastatic insulinoma patient with streptozotocin (a beta-cell toxic chemotherapy drug used to treat insulinomas only), the death of the insulinoma cells can cause a rapid increase in blood insulin activity, leading to severe hypoglycemia. Glucagon infusion should normalize this situation, making the administration of streptozotocin safer and more convenient. Glucagon is typically given as an initial bolus of 50 nanograms/kg IV, then a constant rate infusion between 5 and 15 nanograms/kg/minute is titrated to effect. This treatment is also appropriate for diabetics who receive insulin overdoses where IV dextrose infusion does not result in a rapid return to Normoglycemia. We have been very pleased with the success of glucagons CRI's in our patients at SouthPaws.

Inhalational Therapy for Asthma and Chronic Bronchitis

In human medicine, the use of inhaled glucocorticoids and bronchodilators has largely replaced oral medications in the treatment of bronchial asthma. In a recent study of Canadians with asthma, patients who did not use a glucocorticoid inhaler daily were more likely to die of asthma than those who used their inhalers regularly. Inhaled bronchodilators (ex. albuterol) are used to treat the acute asthma attach, while inhaled glucocorticoids (ex. fluticasone) are used as maintenance therapy to prevent the airway inflammation that results in asthmatic symptoms. The use of inhaled medications results in a decreased dependency on oral medications such as prednisone, with a reductions in side effects (i.e., PU/PD, obesity, increased susceptibility to infections, excessive panting, diabetic management problems). In veterinary medicine, we had a problem with getting our patients to use an inhaler, however there are now new devices available that will work in cats and small dogs to permit the use of standard inhalers. The OptiChamber is a plastic spacing cylinder with a one-way valve that attaches to a flexible facemask. Owners can be taught to use this device - even with small squirming cats - for daily therapy with inhaled glucocorticoids. The cat with an acute asthma attack can be treated with inhaled albuterol, oxygen, and an injection of dexamethasone in the hospital ER setting. We have the OptiChamber available at SouthPaws for emergency in-hospital use and to send home with a stable asthmatic.

Heartworm infection in cats is very difficult to diagnose with confidence. This is due to the low sensitivity and specificity of some of the tests for use in cats and the unique nature of feline dirofilariasis.   

Microfilaria identification (filter  test, blood smear): Less than 20% of cats with HW infections have circulating microfilariae mostly due to frequent unisex infections and the low worm burden. Therefore, these tests have a low sensitivity but high specificity (false positive results are uncommon but false negatives are common). In other words, if you see microfilaria, they are from HW since cats in the US are not infected with other filarial nematodes, but if you do not see microfilariae the cat could still have HW).

HW antigen test (occult HW test): This test identifies antigen associated with the adult female HW. It has a high specificity (false positive is uncommon) therefore, if the antigen test is positive, there is a very high likelihood that the cat is infected

with adult female HW. But this test has a low sensitivity (false negative is common) because of the nature of feline HW infections. Feline HW infections are characterized by 1) low worm burden which might not allow enough antigen to circulate and be detected by blood tests,  2) single sex infections with only male worms. Also infections with female worms less than 5 months old would not be identified by currently available antigen tests. 
HW antibody tests: These tests identify feline antibody to HW larvae. Since exposure to HW larvae is the single most important risk factor for the development of an adult infection, this test may be helpful in predicting the likelihood of infection (i.e., if a cat had a positive HW antibody test, HW is still on our rule out list, but not definitively diagnosed yet). A positive antibody test could represent the presence of adult HW, past infection with adults but now the infection is resolved although antibodies persist, L4 stage or immature adult infection, or false positive. Remember, cats may be able

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