Feline Leukemia Virus
A retrovirus and the cause of more cat deaths (directly or indirectly) than any other organism. Causes cancers (lymphoma, leukemia), blood diseases, immunosuppression, and secondary infections. Highly preventable through vaccination. Transmitted through close social contact — saliva, blood, urine, shared bowls, mutual grooming, bite wounds, and nursing.
Key Facts
- Transmitted via saliva (highest concentration), blood, urine, feces, milk, bite wounds
- Sharing food/water bowls, litterboxes, and mutual grooming can transmit
- Four infection types: abortive (cleared), regressive (limited), latent (dormant), progressive (active shedding)
- Progressive infection: actively shedding virus, likely to develop FeLV-related disease
- Regressive infection: may live normal lifespan with no clinical signs
- Causes: lymphoma, leukemia, bone marrow suppression, anemia, immunosuppression
- 50% of renal-lymphoma cats are FeLV-positive; 80% of mediastinal lymphoma
- No specific clinical signs — disease manifests through secondary conditions
- Kittens most vulnerable; vaccination with recombinant vaccine is highly effective
- Two kitten vaccines + 1-year booster provides strong protection
- Test all new cats; retest 90 days after known/suspected exposure
- FeLV-positive cats should live indoors, away from other cats, with 6-month vet checks
- Virus unstable outside cat — dies within minutes; new cat safe days after infected cat leaves
- Not a human health hazard — no human infection ever documented
- Antiviral treatments (zidovudine, raltegravir) have limited efficacy
Connections (17)
Related Conditions
— transmitted through bite wounds
Co-infection with FeLV can worsen the disease and promote severe bone marrow disorders or cancer.
— often tested together; both retroviruses spread by contact
— another serious retroviral disease to differentiate
— immunosuppression worsens URI
— immunosuppression increases susceptibility
Not a direct cause but FIV may predispose
— FeLV is a major cause; vaccination changed predominant lymphoma form
— also transmitted by bites; test alongside
— half of renal lymphoma cases are FeLV-positive
— immunosuppression increases susceptibility