Digoxin is an anti-arrhythmic drug that was developed using a cardiac glycoside. It is used for treatment of chronic atrial fibrillation, supraventricular arrhythmias, and congestive heart failure in poultry. This drug is potentially toxic to poultry, and the margin between toxic and therapeutic dose is small.
de Wit, Martine, and Nico J. Schoemaker.. Clinical approach to avian cardiac disease Seminars in Avian and Exotic Pet Medicine. Vol. 13. No. 4. Ballweber, Lora Rickard. "Waterfowl parasites." Seminars in Avian and Exotic Pet Medicine. Vol. 13. No. 4. WB Saunders, 2 (2005)