Species Differences in the Changes in Heart Rate and T-wave Amplitude after Autonomic Blockade in Thoroughbred Horses, Ponies, Cows, Pigs, Goats and Chickens

Abstract

Using Thoroughbred horses, ponies, Holstein cows, pigs, goats and chickens, the effects of atropine and/or propranolol on heart rate (HR) and T-wave amplitude (TWA) on ECG were examined. HR increased significantly in all animal species after the administration of atropine, and decreased in the pig, goat and chicken after the administration of propranolol. Parasympathetic predominance, estimated from the changes in HR induced by the autonomic blockers, was in the order of Thoroughbred horse > pony > cow > goat whereas the sympathetic predominance was in the order of chicken > pig. The positive ingredient in TWA was increased significantly in the Thoroughbred horse, pony, pig, and goat by atropine whereas decreased only in the pig by propranolol.