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Feline Immunodeficiency Virus (FIV)

Feline Immunodeficiency Virus (FIV) is similar to HIV in humans, which can eventually lead to AIDS.  This virus causes a weakening (suppression) of the immune system in cats, which means that affected cats are less able to protect themselves against secondary infections, caused by agents like bacteria, viruses,  fungi and protozoa.  Fortunately, this disease is rare in Hong Kong and probably only 1% (or less) of cats are infected with the virus.

 

FIV is a contagious disease that is normally spread from one cat to another by biting and fighting.  Deep bite wounds are the most common form of spreading disease. This helps to explain why intact, aggressive male cats that spend a lot of time outdoors are at a higher risk of catching the virus.  FIV can be spread by other means but these are less common. It is worth noting that mother cats cannot infect kittens except in the initial stages of her infection. Also it is very unlikely that cats living together will transmit the virus by casual contact such as grooming, sharing food and water bowls and sleeping together.

 

Clinical signs

 

Infected cats can appear healthy for several years but eventually, infection will lead to a state of immune suppression – this will lead to an infected cat being unable to protect itself against other infections. The signs of a cat infected with FIV can vary greatly. Depending on which part of the body is affected by secondary (opportunistic) infections, will determine on which signs an infected cat will display.

 

Early infection will often lead to temporarily swollen lymph nodes and a fever followed by either progressive deterioration or periods of intermittent illness.  Once disease develops to cause immunodeficiency, common signs include:

 

·      Loss of appetite, fever and poor coat quality.

·      Persistent diarrhoea

·      Inflammation of the mouth and gums (gingivitis and stomatitis).

·      Weight loss

·      Recurrent infections of skin (e.g. ringworm), bladder and respiratory tract.

·      Other conditions can include diseases that affect the eyes, central nervous system (e.g. brain) and development of certain types of cancers.

 

Diagnostic tests

 

The simplest test is a rapid test, which we can perform in Acorn, which measures the presence of antibodies in infected cats. Because most cats exposed to FIV, will never completely eliminate the virus, the presence of antibodies confirms that a cat is infected with FIV.

 

It is worth noting that antibody tests can occasionally cause false positive results so in these cases, it is worth confirming the result with a test using s different format, e,g, Western Blot in available in commercial laboratories..

Also at Acorn, we do not recommend testing kittens under the age of 6 months since mother cats that are infected with FIV can transfer their antibodies to the nursing kittens causing a positive result.  Many of these kittens are not actually infected with FIV and will not develop disease. To get a true idea of whether a kitten is infected, it is therefore better to test cats after they are 6 months old to ensure there are no maternal antibodies left to cause a false positive.

 

It is also possible to get false negative antibody test results. This normally occurs in the very early stage if infection e.g. a few days after being bitten by an infected cat. The reason for this is that it can take 2-3 months for antibodies to develop. Occasionally, in cats that have very advanced disease due to FIV, a false negative result can also occur due to severely weakened immune systems that cannot develop antibodies any longer.

 

There are other ways to test cats for FIV such as polymerase chain reaction (PCR), which can detect very small amounts of the FIV virus’ genetic material. At present however, PCR tends to not produce very reliable results and we therefore, do not routinely recommend using it to detect infection.

 

Treatment and management

 

Firstly, it is worth noting that an infected FIV cat does not need to be isolated from other cats in the household unless they are likely to fight and bite each other.

 

Lifestyle changes that we often recommend at Acorn are mainly to minimize risk of secondary infections in immuno-compromised cats and include:

·      Infected cats should be kept indoors to prevent infection to other cats and also to minimize exposure to other infections.

·      Regular cleaning of food and water bowls, toys, litter trays etc with bleach to minimize secondary infections.

·      Regular vaccinations (for all cats in household) to prevent risk of secondary infections in FIV+ cats.

·      Regular parasite control against fleas, mites and worms.

·      Healthy diet which is balanced and complete (not raw food exposing an infected cat to possibly serious pathogens).

·      Infected cats should be de-sexed .

·      Close monitoring for any signs in deterioration of health, e.g. weight loss, infected gums, skin or eyes.

 

Although some vets recommend using antiviral agents (e.g. interferon) and immune stimulating agents, there is no convincing evidence that any of these treatments are beneficial.

 

Other treatment options that may be considered are using antioxidants such as superoxide dismutase that may increase the number T-helper cells (lymphocytes) that help to fight infections. Also AZT, which is commonly used in humans with HIV, may help in cases of FIV showing symptoms, such as gingivitis or neurological signs. When using AZT, it is important for us to monitor your cat’s red cell count (as sometimes this drug can depress the numbers of red blood cells).

 

It is difficult for us to accurately predict how long an infected cat can live with FIV. Many cats can live healthy lives for many years. Once cats begin to become infected with severe secondary infections and begin to lose weight, the expected survival may only be months.

 

FIV vaccines are available but we do not routinely recommend them at Acorn as they have not been proven to be very effective, will interfere with testing and may possibly lead to side effects.

 

One last point worth noting is that FIV cannot spread to humans.