Detection of feline leukemia virus infection in saliva

The question was investigated whether feline leukemia virus (FeLV) infection may be diagnosed by testing saliva in an enzyme-linked immunosorbent assay (ELISA). Saliva was collected with commercially available swabs, eluted from the swabs, and tested in the ELISA. A comparison of results with saliva and serum samples from 60 specific-pathogen-free cats, 9 experimentally infected cats, and 1,117 field cats led to the following conclusions. False-positive saliva results, if any occurred, were rare events. During experimental infections, antigen excretion in saliva was observed 1.5 weeks after the first appearance of FeLV antigen in serum. In one of four positive serum samples from sick animals brought to veterinarians, saliva samples tested negative. The use of saliva in an ELISA for the detection of FeLV p27 in individual sick cats is therefore less reliable than the use of serum. In seven cats with diseases typical of FeLV, including one with an intestinal form of lyphosarcoma, saliva tested positive and serum tested negative. Based on the saliva and serum results for cats living in 92 multicat households, it was concluded that saliva may be a useful secretion for FeLV screening.