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Feline leukemia virus (FeLV) PDF Print E-mail

The feline leukemia virus is a retrovirus that causes immunodeficiency and neoplastic (cancer) disease in domestic cats. It is spread between cats by bites, close casual contact (grooming), shared dishes or litter pans. It can also be spread from mothers to their kittens both before and after parturition—fetal and neonatal death of kittens from 80% of affected queens; transplacental and transmammary transmission in at least 20% of surviving kittens from infected queens.

Infected cats that become immunodeficient are susceptible to a variety of infections. Clinical signs that you may notice include lethargy, depression, anorexia, fever, coughing, sneezing, nasal or ocular discharge, gingivitis, tooth loss, skin and ear infections, persistent diarrhea, and weight loss. Infected cats that develop cancer most often develop lymphosarcoma. Clinical signs seen with lymphosarcoma depend on where the cancer originates and most often include anorexia, weight loss, vomiting, diarrhea, unkempt fur coat, or increased respiratory rate and effort.

Persistent infection with FeLV is usually fatal. It is important to either vaccinate your cats or keep your cats indoors and separated from FeLV-positive cats. If your cat has FeLV it is also important to keep it separated from other cats to protect it from diseases that other cats may be carrying. A simple respiratory infection can kill an immunocompromised cat.

All outdoor cats should be tested for FeLV. If they are negative and to remain outdoor cats, they should be vaccinated. If they are positive they should be confined indoors to protect themselves and other neighborhood cats. Indoor cats with no chance of exposure to other cats do not need to be vaccinated against FeLV.