Feline immunodeficiency virus (FIV) in cats

Content by Dr Siân Burwood MRCVS

Feline immunodeficiency virus (FIV) is a viral infection that damages the way a cat’s immune system works. Similar to HIV in humans, the damage to the immune system means infected cats are more likely to suffer with other infections that they would otherwise be able to deal with. It can also make some other diseases, like cancer, more likely.

FIV is spread through contact with infected cats, and does not cause specific symptoms. It can be highly contagious to other cats if they fight – so while infected cats can live out normal lifespans, they must be kept as indoor cats.

FIV can only affect cats. It’s not a risk to humans or other animals.

• Feline immunodeficiency virus (FIV) is a viral infection that affects cats’ immune systems
• It develops very slowly, and signs of disease may not be seen for 2-5 years after infection
• It’s spread by saliva. Cat bites are the most common way for this to happen
• It cannot be cured. How serious the disease is depends on what (if any) secondary infections develop, and how healthy the cat is otherwise
• FIV-positive cats can live out normal lifespans, but must be kept in such a way that they don’t risk spreading infection to other cats

FIV is caused by the feline immunodeficiency virus. This belongs to a group of viruses called lentiviruses, which all cause disease slowly – sometimes many years after infection.

FIV is mostly spread through cat bites, as the virus is always present in the saliva of infected cats. It can very rarely be spread by mutual grooming, and if a pregnant cat is infected it can spread to her kittens. It’s not known whether blood-sucking parasites like fleas can spread infection or not.

FIV does not survive for long in the environment, and so regular cleaning and stopping spread via saliva is the best way to manage it.

There’s no breed most affected by FIV infection. But there are types of cats who are more at risk – especially those who live in large groups of unneutered cats, where there’s more likely to be fighting and bites.

Male cats are twice as likely to be infected as female cats, and outdoor cats are more likely to be affected than indoor cats.

FIV doesn’t have any specific signs or symptoms, and it may often present looking like something else. Your vet may suspect FIV from your cat’s history (for example in male cats that go outside and fight a lot), or if they keep being seen with recurrent infections that don’t seem to get better as expected.

Signs that might suggest FIV infection include:

• Weight loss
• Recurrent fevers
• Lethargy
• Inflammation of the gums and mouth (stomatitis)
• Enlarged lymph nodes
• Ongoing diseases of the eyes, lungs, guts or skin
• Neurological disease
• Cancer
• Unusual infections

Diagnosis

FIV can be easily and reliably diagnosed by a simple blood test. This can often be done at your vet practice, although some will want to send it off to an external laboratory.

FIV is a disease that’s managed, not treated. Treatment will be provided for whatever secondary infections your cat might be showing: pain relief for inflammation, antibiotics for infections, supportive care for fevers and loss of appetite. When another disease – such as cancer – develops due to underlying FIV infection, the treatment will be focused on what that is, rather than dealing with the FIV itself.

FIV infection cannot be cured. There aren’t currently any safe antiviral medications for this. Management of FIV is focused on stopping the spread of the disease through:

• Neutering
• Keeping cats in stable social groups
• Maintaining good preventative healthcare through regular vet checks, good diet, vaccination and parasite treatment

Some cats infected with FIV may never go on to develop clinical disease, and for them the prognosis is excellent. The most important thing is to know (if at all possible) whether a cat is FIV positive, so that their lifestyle can keep them and other cats safe, while reducing spread.

If a cat does go on to develop disease secondary to FIV, prognosis depends on what that is and how healthy the cat is otherwise. A cat in a stable home with, say, dental inflammation can be managed well and live out a normal lifespan. A cat who still goes outdoors and develops lymphoma will have a much poorer prognosis.

“FIV is something that’s always at the back of our minds as vets when dealing with a cat who keeps getting the same infection, or who isn’t responding as we would hope.

“I often see FIV-positive cats who have been rescued and live out a healthy and happy life as a house cat. The more concerning thing we see is the unneutered cat who’s allowed to roam freely and get into fights, as they’re adding not only to the cat over-population problem, but also to the spread of FIV.

“I often wonder how many of the later-life cancer cases I see are maybe related to the bite the cat received many years ago. As always, keeping up with preventative care and regular checks is the best way forward.”

Dr Siân Burwood MA VetMB MRCVS

If you’re thinking about buying a Petgevity Lifetime Plus policy, we’ll consider all pre-existing conditions when offering cover for your cat* – including FIV.

When you apply for cat insurance, you need to let us know: 

• Which medical conditions they’ve had in the last two years 
• Their health status now

Find out more about Petgevity’s cat insurance for pre-existing conditions.