What is feline leukemia virus?
Feline leukemia virus (FeLV) is a virus that infects cats. FeLV depresses the immune system and cats tend to remain infected for life. FeLV is an important cause of anemia in cats and can cause several types of cancers. It is found worldwide and is transmitted through the exchange of bodily fluids, such as from a bite or prolonged exposure to an infected cat’s saliva, urine or feces. It can also be transmitted from mother to kitten.
There is no treatment to eliminate the FeLV virus from the body and the disease is ultimately fatal. For that reason, preventing FeLV infection through vaccination is highly recommended.
Is there a test for FeLV infection?
Special blood tests can detect the presence of FeLV in a cat's blood. In general, these tests are reliable, although rarely, a false positive result can occur. In some situations, it may be necessary to confirm infection by repeating blood testing or performing different types of analysis, such as PCR testing.
Does my cat need a blood test before vaccination?
Most cats should have a blood test before being vaccinated to determine whether they have been infected with the FeLV virus. If your cat tests positive for FeLV, there is no benefit in administering the vaccine, as it will not offer any protection against the virus. Vaccination does not interfere with the FeLV blood test.
How safe is the vaccine?
FeLV vaccines are safe and there is no risk of the vaccine causing FeLV. Vaccine reactions are rare in cats; however, any vaccine may cause transient, mild side effects for a few days after vaccination, such as lethargy and low appetite. Call your veterinarian immediately if your cat shows more pronounced signs, such as difficulty breathing, as they may be allergic to one or more components of the vaccine.
Swellings at the site of vaccination can also occur and may resolve on their own in a few weeks to months. These should be monitored closely as injection-site sarcomas can develop after any injection and need to be removed surgically. Notify your veterinarian of any concerns after vaccination. Your veterinarian will weigh the benefits and risk of vaccination. In most cats at risk of exposure, the benefits far outweigh the risks.
How effective is FeLV vaccination?
FeLV vaccines have been available for many years and have been continuously improved. They are helpful in preventing infection with FeLV and controlling FeLV-related disease. Unfortunately, no vaccine is 100% protective, though effectiveness has been shown to be between 80% and 93%.
The Feline Veterinary Medical Association (FelineVMA) currently recommends FeLV vaccination for all kittens, then vaccination one year later, and then as needed for adult cats. Although the FeLV vaccine is not considered a core vaccine in adult indoor cats, it is highly recommended for cats that spend time outdoors. Your veterinarian can discuss the advantages and disadvantages of vaccinating your cat against this disease based on their lifestyle and risk of exposure.
The incidence of FeLV disease has dramatically declined over the past several decades, likely due to a combination of the availability of accurate screening tests, improved client awareness of the disease, a change in the lifestyle of the average cat (more cats are kept indoors rather than allowed to roam freely), and vaccination of at-risk cats.
How often should my cat be revaccinated?
In the initial vaccination series, two doses of vaccine are administered one month apart, which is necessary to provide strong, lasting immunity. Even so, this immunity will decline over time and periodic revaccination will be necessary. Your veterinarian will advise you about the recommended revaccination schedule based on your cat's lifestyle and needs.