Feline Immunodeficiency Virus (FIV)

What is FIV?

FIV (Feline Immunodeficiency Virus) is a potentially fatal viral disease that weakens the immune system of cats. Vaccination is recommended for all cats that are allowed outside of the house.

How prevalent is FIV infection in Australia?

It is reported that between 14 and 29% of cats in Australia test positive to the disease. Prevalence varies with location – with higher prevalence in NSW and WA.

How do cats get FIV?

FIV is spread between cats primarily through biting with the virus shed in high levels in the saliva. Outdoor cats are therefore at highest risk for contracting infection especially if they are involved in breeding, fighting or have a history of cat fight abscesses. Normal social interaction through grooming and sharing feed bowls is considered to have a very low risk of transmitting FIV. The virus does not survive long in the environment.

How is FIV diagnosed?

FIV can be diagnosed using an in-house blood test which looks for an immune response (antibodies) to the virus. If this test is positive it is likely that your cat has been infected by the virus.

FIV testing is recommended for any cat presenting with a cat fight abscess or other cat fight wounds and all sick adult cats. Adult cats prior to being FIV vaccinated for the first time should also be tested, as should cats sharing a household with a test positive cat. The timing and the type of test used is very important and our veterinarians will recommend the best test for your cat. Refer to “More Information on FIV Blood Testing” at the end of this document.

How do you stop cats becoming infected?

The risk of infection can be minimised by making sure your cat is housed indoors. If confining your cat indoors 100% of the time is not possible, then at least confine them to a garage/laundry at night as this is the most common time for cat fights and have your cat desexed to reduce territorial behaviour.

Cats can now be vaccinated with an FIV vaccine.

Vaccinating cats for FIV

There are 5 subtypes of FIV. Vaccination protects against subtype A which is the most common Australian subtype.

There is no need to vaccinate cats which are to be housed 100% indoors (unless housed with an FIV positive cat).

Kittens – Require 3 vaccinations at intervals of 2-4 weeks from 8 weeks of age. Annual boosters are then required for life to maintain immunity.

Adult Cats – Cats which have only ever been housed indoors can be vaccinated as for kittens without prior testing (unless in-contact with a known positive cat). Outdoor adult cats (over 6 months of age) vaccinated for the first time require an FIV test to ensure there is no existing FIV infection. Refer to section “The Importance of Test Selection and Timing” at the end of this document.

My cat has tested positive to FIV – Does this mean my cat has Feline AIDS?

If your cat has tested positive for FIV – it is not the same as having feline AIDS. AIDS describes the terminal stages of disease which may not occur for many years – if at all! FIV positive simply means that your cat has been infected by the FIV virus.

Is my family at risk?

There is no risk of a human catching HIV/AIDS from a cat with FIV.

Are other cats in my household at risk?

If the cats in your household get on well (do not fight) then there is a low risk that in-contact cats will become infected. It is likely that other cats in your household may already be infected if they too have been involved in fights. All in-contact cats should be tested and vaccinated

Will my cat recover?

If a cat becomes infected with FIV it remains infected for life. Not all cats with FIV will develop disease as a result of their infection but FIV infected cats will generally have a shorter life.

What type of disease does FIV cause?

FIV causes disease because it alters the cat’s immune system so it becomes less able to respond to other infections in the normal way. Often infected cats will develop chronic or recurrent infections that fail to respond to treatment in the normal way.

Common clinical signs of FIV infection that have been reported include:

• Loss of appetite
• Fever
• Lethargy
• Conjunctivitis
• Swollen lymph nodes
• Vomiting and diarrhoea

As the disease progresses:

• Weight loss
• Poor coat quality
• Chronic infections
• Gingivitis
• Sores in the mouth

A lot of these signs are very non-specific and many diseases can have similar symptoms.

Is there any treatment?

Secondary infections can be effectively treated with antibiotics etc. but no specific treatment for the virus is available.

Should I have my cat euthanased?

Cats should not be euthanased simply on the basis of being FIV positive.

Cats with FIV have a long period where they appear healthy and show no clinical signs. This period can last for many years during which your cat can have a normal, happy life. If your cat tests positive then you simply need to investigate and treat their other problems as they occur.

How can I help my cat?

You can help your cat by ensuring it has a healthy lifestyle and good quality food together with regular worming and yearly booster vaccinations. Any infections should be treated promptly and aggressively. The healthier a cat is the longer the asymptomatic period tends to be. Keeping your cat indoors is also a good idea as it reduces the likelihood of your cat picking up other infections as well as reducing the spread of the FIV virus.

One cat in my household is FIV positive and the others are not – what should I do?

Standard advice is to house FIV positive cats indoors to reduce the risk of spread to other cats. While this is good practice for a single cat household, it is far better advice in a multi-cat household to house your FIV NEGATIVE cats indoors to prevent them from becoming infected.

You may choose to re-home your FIV positive cat to a house with no other cats.

However, if your cats get along well (don’t fight) then you may choose to keep your FIV positive cat, as the risk of infection spreading by social contact is low. All other cats in the household should be tested and vaccinated.

FIV Blood Testing

Tests used at Macarthur Veterinary Group

SNAP FIV antibody tests

This is a convenient in-house test providing results within minutes. Its main limitation is that antibodies to FIV can take 3 months to develop following infection. It will test falsely positive in:

• FIV vaccinated cats and
• kittens carrying maternal antibodies

PCR antigen tests

This type of test requires blood to be sent off-site to a veterinary laboratory. Antigen tests are not affected by prior FIV vaccination or the presence of maternal antibodies. It will detect infection as early as 1 month after exposure. It is best not to use this test first as it is more likely to result in false negatives (less sensitive test).

The Importance of Test Selection and Timing

False positive tests

Kittens under 6 months of age may falsely test positive if maternal antibodies to the virus have been passed on to the kitten via the milk of their infected or vaccinated mother. Kittens testing positive with a SNAP test must be retested after 6 months of age with the SNAP test or at any time using a PCR test.

Cats can also falsely test positive to the in-house SNAP test if they have previously received an FIV vaccination as these cats will develop FIV antibodies as a response to the vaccine which can last up to 4 years. If a false in-house positive is suspected due to possible previous vaccination then repeating the test using a PCR antigen test is recommended.

False negative tests

Can occur in cats only very recently exposed to the virus. Where recent infection is possible (i.e. fighting cats about to be vaccinated and cats presenting with cat fight wounds) then repeat testing with a PCR antigen test 1 month later is recommended (the cat should be confined indoors during this time to prevent new exposure).

By Macarthur Veterinary Group

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