Effects of aspirin and propranolol on feline platelet aggregation.

Three groups of cats were given aspirin in single dosages of 5, 10, and 25 mg/kg. A 4th group was given 2 dosages of 25 mg/kg, 3 days between doses. The degree of inhibition of platelet function and the duration of antagonism to platelet aggregation were studied. The dosage of 25 mg/kg (single and repeated) consistently inhibited platelet function, and the effects lasted 3 to 5 days. Additive drug effect was not noted in group 4, since the 2nd dosage antagonized platelet function to a degree and duration similar to the effects of the 1st. The dosage of aspirin recommended for antiplatelet activity in the average-sized cat (3 kg) equals approximately 1 pediatric aspirin (90 mg) given twice a week. Propranolol, given to cats at dosages of 2.5 to 15 mg had no effect on platelet aggregation.