Understanding Feline Leukemia Virus (FeLV) and Its Symptoms
Feline leukemia virus (FeLV) is one of the most common infectious diseases in domestic cats, affecting approximately 2–3% of cats in the United States and Canada. It is highly contagious and poses a significant risk to a cat’s overall health, with varying symptoms that depend on the progression of the disease.
What Is Feline Leukemia Virus?
FeLV is a retrovirus that weakens a cat's immune system, increasing the risk of infections, anemia, and cancer. Although often asymptomatic in early stages, FeLV can lead to fatal health issues, especially in progressive infections where the virus remains active in the bloodstream.
How Is FeLV Transmitted?
FeLV spreads primarily through saliva, but can also be found in urine and feces. Common transmission routes include:
- Mutual grooming
- Bite wounds
- Shared feeding dishes and litter boxes
- From mother cat to kittens (before birth or during nursing)
Because FeLV cannot survive long outside a cat’s body, transmission typically requires prolonged and close direct contact.
Risk Factors
Certain cats are more susceptible to FeLV infection, including:
- Cats living with infected or untested cats
- Outdoor or free-roaming cats
- Cats in crowded environments (shelters, catteries)
- Kittens and young cats (less natural resistance)
Indoor-only cats with no exposure to outside felines are at minimal risk, but owners should still take preventive measures.
Stages and Types of Infection
Upon exposure, cats may experience one of several outcomes:
- Abortive infection: The cat's immune system completely eliminates the virus, rendering it non-contagious. This outcome is rare.
- Regressive infection: The virus is isolated in certain tissues, typically the bone marrow. The cat does not appear contagious but may later develop symptoms if immune suppression occurs.
- Progressive infection: The virus remains in the bloodstream, making the cat contagious and prone to infections and cancers. Most FeLV-related deaths result from this type.
Symptoms to Watch For
FeLV symptoms can vary significantly or take a long time to appear. Common clinical signs include:
- Appetite loss and weight loss
- Poor coat condition
- Persistent fever
- Lethargy and malaise
- Swollen lymph nodes
- Pale or yellow gums
- Stomatitis and gingivitis
- Secondary infections (respiratory, bladder, or skin)
- Diarrhea and vomiting
- Neurological signs (seizures, behavioral changes)
- Eye problems
- Reproductive issues (abortions, sterility)
- Anemia
- Lymphoma or other cancers
Diagnosing FeLV
Diagnosis typically involves a combination of the following tests:
- ELISA test: Detects viral antigens in early infection stages
- IFA test: Confirms long-term infections by identifying infected blood cells
- PCR test: Detects viral DNA within a cat’s genome, useful for identifying regressive infections
Because FeLV stage can change, repeat testing after several weeks may be needed to confirm diagnosis.
Treatment Options
Currently, there is no cure for FeLV. Treatment focuses on managing symptoms and improving quality of life:
- Antibiotics for secondary infections
- Blood transfusions if anemia is severe
- Chemotherapy for cancer-related complications
- Immune-modulating drugs
- Supportive care including proper nutrition and hydration
Cats with proper care can live months or even years post-diagnosis, especially those with regressive infections.
Prevention and Home Care
Preventing FeLV spread and progression is vital for all cat owners. Recommended actions include:
- Keep cats indoors to minimize exposure risks
- Avoid mixing FeLV-positive and healthy cats
- Test all new cats before introducing them to existing pets
- Spay or neuter to reduce territorial aggression
- Vaccinate kittens and at-risk adults (effective only for FeLV-negative cats)
Living With FeLV-Infected Cats
With attentive care, FeLV-positive cats can live fulfilling lives. Owners should:
- Protect FeLV cats from potential infections by limiting their contact with other animals
- Monitor for signs of illness such as reduced appetite, energy, or changes in behavior
- Provide regular veterinary check-ups and prompt treatment when symptoms arise
FeLV-infected cats pose no risk to humans or other non-feline pets.
Conclusion
Feline leukemia is a serious but manageable disease. Understanding symptoms and providing proactive care can improve outcomes and extend your cat’s life. Regular testing, vaccination, and close monitoring are the best defenses against the impact of FeLV.
