Feline Leukemia (FeLV) and Feline Immunodeficiency Virus (FIV) are both caused by retroviruses that can be transmitted it to other cats. Both viruses depress the immune system opening the door to secondary infections and diseases. The most common contagious infection is upper-respiratory. The most common non-contagious disease is cancer.

An individual cat can contract both FeLV and FIV.

Contracting the viruses:

FeLV is spread through close and prolonged cat-to-cat contact through bodily fluids (saliva, blood, urine and feces). Mother cats can give it to their kittens when they are pregnant or when they are nursing. Companion cats can spread it through shared food and water dishes and through mutual grooming.
FIV is spread when an infected cat bites another cat. This can happen when cats fight so unneutered male cats that are allowed outside have the highest risk of infection.

Progression and Symptoms:

FeLV can be caused by one of several types of viruses which have slightly different symptoms.
In the early stages, common symptoms include weight loss, dehydration and fever.
FIV also has a wide ranging group of symptoms. Since the immune system is depressed, upper respiratory infections can become chronic. The mouth can become inflamed there can be loss of weight due to chronic diarrhea, fevers, enlargement of the lymph glands, and chronic abscesses. Younger, healthier cats can live for years with the disease in remission.


There is a vaccine for FeLV although it may not be 100% effective. Your personal veterinarian will be able to discuss the pros and cons of vaccinating individual cats.


There is no cure for either FeLV or FIV. Some cats can live long and healthy lives while others contract diseases immediately. Blood tests can show the presence of both viruses. Your veterinarian should always be notified if your cat has been infected since this could affect his administration of vaccines and other treatments.

Remember: An infected cat should be kept away from uninfected cats. A healthy, balanced and nutritious diet and good general care is the best way to maintain your cat’s health for as long as possible. Minimizing stress and change is also helpful.