Feline AIDS was first discovered in the USA in the 1980s, when a group of cats showed signs similar to people with acquired immunodeficiency disease (AIDS). In humans this condition is caused by human immunodeficiency virus (HIV). In cats a related virus, feline immunodeficiency virus (FIV), is the cause. Although related, these viruses cannot cross species. An infected cat poses no risk to humans, and vice versa. Infected cats can remain healthy for years, but eventually it affects their immune system, making them susceptible to infections of all kinds.
What is FIV and how cat my cat catch it?
FIV is in the group of viruses called lentivirus, in the family called retroviruses. There are several strains. None survive well in the outside world, and they are easily killed by disinfectants. It is present in the saliva of infected cats. The most common way it is spread is by biting, the virus being injected under the skin. Cats that groom each other or eat from the same bowls are at risk, but the risk seems to be low. Kittens with an FIV positive mother can become infected with the virus.
What signs might there be?
At infection there may be a short episode of fever and enlarged lymph nodes, or no signs at all. The cat produces antibodies, reducing viral levels, but once infected, unlike many other viruses, the cat will never fully eliminate it. The virus replicates slowly, and further signs may not be seen for years (typically 2-5). Immune system cells are slowly infected and damaged, making the cat more prone to infections.
As the cat can become infected with a host of other infections, signs vary. Recurring infections that may not respond as expected are seen. Fever, lethargy, weight loss, enlarged lymph nodes, diarrhoea, or respiratory disease can occur. Gum disease (gingivitis) and certain types of cancer, such as lymphoma, may be linked to FIV infection.
How common is it?
It is thought that in healthy cats 1-5% are infected. This varies a lot. For example, a group of cats living together in a colony are more at risk than indoor cats. It is most often diagnosed in middle aged cats, when symptoms start.
How is it diagnosed?
Our vets can perform a simple in-house blood test to check for antibodies. Once cats are infected with the virus, they remain infected for life, so antibodies are proof of infection. These tests are quite reliable, but if there is doubt, blood can be sent off to a laboratory for further testing. Young cats may have antibodies from their mother, so should not be tested until at least 3 months after weaning.
How is it treated?
Most cats, once infected, have years of good health, or may never show signs. It depends on the strain of FIV, the cat’s immune system, and the risk of exposure to other infections.
FIV has no cure. As the symptoms are more related to other infections rather than FIV itself, there is no specific treatment. Antivirals do exist, but they are expensive, can have side effects, and their effectiveness in changing the course of the disease is uncertain.
As other infections are generally the cause for illness, it is best to prevent exposure to other diseases. Infected cats should be kept indoors. This reduces the risk of infecting other cats, but also the risk of exposure to other infections. They should be neutered, as this will reduce the risk of fighting, and wanting to stray. Feeding a good quality diet and avoiding raw foods that may harbor infections is important. Although it is not known if fleas can transmit the virus, regular flea and worming treatments should be given to maintain general health.
Giving routine vaccinations to FIV positive cats is controversial. Advice may depend on the level of risk of exposure. For example, if the cat is elderly, or only indoor, they are at low risk. If the cat goes out (which is not ideal) then vaccinations are essential. Our vets can discuss the pros and cons of vaccinating a FIV positive cat with you.
Prompt treatment for any secondary infections by our team is vital. The earlier signs are treated, then more likely there will be a response.
Is there anything I can do to prevent my cat getting FIV?
Neutering cats early, especially males, will reduce the likelihood of fighting. Keeping your cat indoors will prevent fighting, but there are other potential risks for indoor cats. Our vets can talk you through the risks and benefits of indoor versus outdoor lifestyles.
If you have an FIV positive cat housed with others, isolating all cats then testing them is ideal. If they are negative three months later, rehoming should be considered to prevent infection. If this isn’t possible, and nor is permanent isolation of the infected cat, then separate feeding bowls and good disinfection is important. Risks of spread are low from grooming and sharing bowls, but if the cats fight the risks are considerable.
No vaccine exists in the UK. There is one used in other parts of the world, but as there are many strains, it does not provide complete protection. It produces antibodies in reaction so it's important to remember cats will test positive on blood tests, but may, or may not, be infected.
Although infection with feline AIDS may sound scary, most cats will live for years without signs once infected. You can reduce the likelihood of signs by: feeding a healthy diet, preventing parasites, using vaccines, and reducing exposure to other infections. There is no need to consider euthanasia on the basis of a positive FIV test if your cat is healthy. However if your cat is very sick at the time of a positive test, the prognosis is guarded, and it may have to be considered. Our team can answer any further questions about this often misunderstood virus.