Evaluation of feline leukemia virus diagnostic tests available for in-office use by veterinarians

Blood samples from cats were tested for FeLV group-specific antigen by use of an indirect immunofluorescent antibody (IFA) test, ELISA, or both. Several ELISA kits were evaluated as they would be used in a veterinary clinic, and some ELISA kits were compared with an IFA test for agreement of results. Good agreement of results was evident among the commercially available ELISA kits; results for most blood samples were clearly negative or decidely positive. Occasionally, test results were equivocal and retesting was necessary to obtain clear interpretation. Negative results are highly reliable, which makes ELISA valuable screening tests for FeLV in healthy cats. Results of tests on blood from healthy cats in Alabama indicated positivity rate of 4.0% in 1978 with an IFA test and 4.8% with ELISA in 1988 through 1989. Infection rate in sick cats ranged from 11.6 to 35.8%. The frequency of positive test results for FeLV in cats tested at Auburn University decreased from a 5-year average of 27.7% during 1980 through 1984 to a 5-year average of 14.9% during 1986 through 1990; the rate in 1990 was 11.6%.