Toxicity of Alpholate to Cattle.

Although Apholate is used as a sexual sterilant of both sexes of houseflies (Musca domestica L.) it can not be used for ;systemic' chemosterilization of the prehypodermic larvae of the warble flies Hypoderma bovis (L.) and H. lineatum (De Vill.) because of its high toxicity to 4- to 5-month-old calves. An intramuscular dose of 2.5 mg./Kg. killed the calves in 5 to 7 days. The pathognomonic clinical signs were impaction of the rumen, anorexia, depression, and general weakness. The hematopoietic system was affected. There was marked leukocytopenia characterized by lymphocytopenia within 24 hours of Apholate injections.