COMPARISON BETWEEN PUPPIES AND ADULT DOGS FOLLOWING INFUSION OF DIGOXIN

Abstract

The purpose of this experiment was to determine if 3-5 week old Puppies, compared to adult dogs, require proportionately larger doses of digitalis. Digoxin 5 μg/kg body Weight/minute (min) was infused until a strain gauge arch on the left ventricle reached a 30% increase in the force of contraction. At that time serum and myocardial specimens were taken to measure digoxin levels by radiomimmunoassay. Puppies reached 30% increase in force at 23.4(SEM 1.3) min compared to 23.0(SEM 2.7) min in the adult dogs. Correspondingly the total amount of digoxin infused was not different between puppies and adult dogs, 117.0(SEM 6.5) versus 115.0(SEM 13.3)μg of digoxin/kg body weight. There was no significant difference in the serum and myocardial digoxin values between puppies and adult dogs. In other dogs digoxin was infused until digitalis toxicity was produced. Puppies required significantly greater amounts of digoxin before toxicity ensued. Puppies averaged 53.5(SEM 1.3) min infusion of digoxin before reaching toxicity; whereas adult dogs became toxic at 29.0(SEM 2.3) min. These experiments confirm that puppies tolerate proportionately larger doses of digitalis without becoming toxic; however the relatively larger dose of digitalis usually given to the young animal may not be necessary for an equivalent inotropic response.