Distempter vaccination of dogs: factors which could cause vaccine failure.

Distemper vaccination failures are uncommon. A number of factors which could cause such failure are discussed. The blocking effect of maternal antibody can be expected in 50% of pups at six weeks but is not important after 12 weeks. Among intercurrent infections, the immunosuppressive effect of parvovirus has the potential to precipitate vaccine-induced distemper. Corticosteroids at levels up to 10 mg/kg do not interfere with successful distemper vaccination. Anesthesia or surgery has little effect but use of chloramphenicol or tetracyclines should be avoided. High environmental temperatures can lead to vaccine failure, as can vitamin E deficiency. Excessive environmental exposure to virulent distemper virus can overcome levels of protection which would be adequate under normal circumstances.