Atrial fibrillation in the cow, pig, dog, and cat.

Atrial fibrillation (AF) is the most frequently observed arrhythmia in milking cows. About 50% of AF-affected cows have a history of ketosis, suggesting a relationship between AF and ketosis. Clinical signs of AF include a sudden decrease in milk production and an unstable appetite. Oral administration of quinidine is effective in the treatment of AF. AF in the pig has been observed only in one breeding animal. The clinical signs included anorexia and abnormal heart sounds. The AF was successfully terminated by the administration of 10 mg/kg quinidine every 8 h. AF in dogs and cats appears as a sign of cardiac failure, although AF may also be observed in large dogs without any underlying cardiac disease. Direct current defibrillation is effective in the treatment of these animals.