Hey Dr. Kate, what is Feline Leukemia Virus and Feline Immunodeficiency Virus?
Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are two viruses found in cats worldwide. These viruses belong to the Retrovirus family, which also includes human immunodeficiency virus (HIV). FeLV and FIV infections are associated with a variety of clinical signs and can impact quality of live and longevity of infected cats.
What is the difference between FeLV and FIV?
FeLV and FIV are categorized as retroviruses, which means they integrate into the cat's own DNA sequences as part of their mode of infection. Infection with either virus tends to cause immunosuppression. The difference is that FeLV tends to infect more "social" cats, while FIV tends to infect cat that roam and fight ("feral" cats). In addition, there is an effective vaccine against FeLV. There is currently no approved vaccine in the US against FIV.
What are the signs of infection with FeLV? With FIV?
The clinical signs of infection tend to be similar. Both viruses suppress the immune system and leave infected cats susceptible to chronic bacterial infections, cancer (lymphosarcoma), and/or chronic oral disease (gingivitis, stomatitis, periodontitis). Cats infected with FeLV tend to get sicker faster, and usually die or are euthanized within a couple years of diagnosis. Cats infected with FIV, on the other hand, tend not to get as sick as fast. With good preventative health care and proper management, many FIV-positive cats live as long as uninfected cats.
How does my cat get infected with FeLV? With FIV?
FeLV is transmitted through close contact between cats. Virus is shed in saliva, nasal secretions, milk, urine and feces. Modes of infection include from an infected queen to her kittens (while pregnant, nursing and grooming), cats that live together and groom each other, or among cats that fight. Most cats are thought to be infected through exposure to oronasal secretions. This makes the infection more common in "social" cats.
FIV is shed in saliva, and the most common mode of transmission is through bite wounds. This make the infection more common in "feral" cats. Unlike FeLV, FIV is not thought to be transmitted from queens to their kittens.
How do you test for these viruses in cats?
Testing for FeLV and FIV involves taking a small blood sample from your cat and testing it for antigens or antibodies to the viruses. At Lakes Veterinary Hospital, we use a commercial in-house test (SNAP Triple Feline Test) that will determine not only if a cat is positive for FeLV or FIV, but also if the cat is infected with heartworms (For more information on heartworm disease, see "Ask Dr. Kate - Heartworm Disease").
When should I test my cat for FeLV and FIV?
All cats should be tested prior to beginning the FeLV vaccine series. This includes kittens up to one year of age, and cats at risk for FeLV/FIV infection (outdoor cats, cats in multi-cat households, cats in close contact with known infected cats). In addition, testing may be warranted in sick cats that do not respond to routine veterinary care. Examples include cats with recurrent abscesses, severe oral disease, respiratory tract infections, evidence of anemia, or fevers of unknown origin.
What does a positive FeLV or FIV test mean?
A positive test result to FeLV or FIV needs to be interpreted in context with the cat's age, health status and vaccine history. For example, test results in kittens can be confounded by the presence of maternal antibodies to FeLV or FIV, or previous vaccination of the queen against FeLV. In addition, cats tend to be come resistant to FeLV infection with age. Cats that have been vaccinated against FIV will continue to test positive on blood tests. This is one of the reasons why the FIV vaccine is not currently available in the United States.
How do I prevent my kitten or cat from getting FeLV or FIV?
Preventing FeLV involves vaccinating AND preventing or limiting access to other cats that might spread the virus. Preventing FIV also involves preventing access to other cats that are infected with the virus; there is no currently approved FIV vaccine to prevent the disease.
What do I do if my kitten tests positive or FeLV or FIV?
A positive FeLV or FIV test result in a kitten does not necessarily mean the kitten is infected with either virus. The presence of maternal antibodies (through nursing) may result in false positive test results in kittens. At Lakes Veterinary Hospital, if your kitten tests positive for either FeLV or FIV, we recommend retesting in 6 months. FeLV vaccines are administered after confirmation of a negative FeLV test result.
What do I do if my adult cat tests positive for FeLV or FIV?
That's a little more complicated. If a cat is clinically healthy and tests positive for FeLV or FIV on the in-house test, we may recommend additional testing through an outside laboratory. This may be especially important if there are other cats in the household to consider. Alternatively, retesting can be performed in 6 months. If the cat continues to test positive for FeLV or FIV, we can advise you of steps to manage your cat's health and welfare. If your cat is FeLV positive, FeLV vaccines are not recommended, and will not be helpful.
If the cat is ill (for example, is running a fever, lethargic, has a history of cat bite abscesses, has severe dental disease, has stopped eating), then a positive test result most likely indicates that the cat is suffering from underlying immunosuppression due to infection with FeLV or FIV. This will have an impact on medical decisions and further treatments for the cat.
My cat is FeLV or FIV positive. What can I do to keep my cat healthy and disease-free for as long as possible?
The best thing that can be done to keep a FeLV- or FIV-positive cat healthy is to keep the cat indoors and away from other cats, especially those of unknown health status. Infected cats should be fed a high quality commercial feline diet and fresh water. The second-best thing is regular physical examinations by your veterinarian. Bacterial and parasite infections (for example, respiratory and urinary tract infections, diarrhea) should be treated promptly and aggressively with appropriate medications. Periodic lab work (CBC, blood chemistry, urinalysis) may be recommended to check for anemia and to monitor the response of bacterial infections to antibiotic therapy. Radiographs may be recommended to check for evidence of pneumonia or cancer. Good oral hygiene is also important: teeth should be cleaned and polished on a regular basis to minimize plaque accumulation, gingivitis and tooth root abscesses. For further information, contact us at Lakes Veterinary Hospital. We can help you provide the best quality of life for your FeLV- or FIV-infected cat.