What is Feline Immunodeficiency Virus?
Also known as FIV or cat AIDS, feline immunodeficiency virus is an infectious disease caused by a retrovirus belonging to the lentivirus family. It is in the same family as the feline leukemia virus (FeLV) and is similar to the HIV virus in humans. FIV infects both domesticated cats, lions, tigers, pumas and cheetahs.
FIV attacks the cells of the immune system, leading to FAIDS (feline acquired immune deficiency syndrome). This compromises the cat's ability to fight off infections.
It was first discovered in 1986 in a colony of cats in California and is found worldwide.
What does FIV do and what are the symptoms?
FIV attacks the cat's immune system which makes it vulnerable to secondary bacterial, viral, fungal and protozoal infections.
Stage 1: Once inside the body, FIV is carried to the regional lymph nodes where it replicates in the white blood cells known as T lymphocytes (CD4+ lymphocyte). It then spreads to other lymph nodes throughout the body. At this time there may be an acute illness which is characterised by fever, leukopenia, anemia, malaise and swollen lymph nodes, lasting a few weeks. During this initial stage, it may go unnoticed that the cat is unwell.
Stage 2: This is the asymptomatic phase which can last for many years. During this stage, the cat appears healthy and is able to lead a normal life.
Stage 3: As we've already discussed, FIV destroys the T lymphocytes, these cells are required for the proper functioning of the immune system. Eventually, when enough T lymphocytes have been destroyed, the immune system loses its ability to fight off opportunistic infections and signs of immunodeficiency develop.
Cats show a range of symptoms in this stage, these symptoms may vary from cat to cat. Some of which may include:
How is FIV transmitted?
The virus is present in large quantities in the cat's saliva, and the most common mode of transmission is via bite wounds. Free roaming, entire male cats are at greater risk as they are more likely to become involved in territorial fighting.
Occasionally FIV is passed onto kittens who's mother is FIV positive. This may happen either in utero or via infected milk.
Cats don't become infected via mutual grooming, nor will the act of mating, although the biting that goes along with mating may pass on the virus.
How is FIV diagnosed?
FIV is diagnosed based on history, clinical signs and a blood test known as ELISA (enzyme-linked immunosorbent assay), which detects antibodies to FIV. It is possible to get false positive or false negatives from these results for the following reasons:
If a cat has received the FIV vaccine it will have a positive test result.
Kittens born to FIV-infected mothers may have received antibodies from their mother's milk. This doesn't mean that the kitten has FIV, just that he's received antibodies to FIV. Kittens who test positive should be re-tested at a later date.
It usually takes several weeks for antibodies to FIV to appear in the blood, if the cat is tested prior to this it will show a negative result.
If the cat is in the later stages of infection it may not be producing antibodies.
An FIV PCR (polymerase chain reaction) test is available in some commercial laboratories. PCR detects the presence of the FIV virus in the blood.
Western blot test or IFA (Immuno-Fluorescent Antibody Test): If a cat has tested positive for FIV it is sometimes recommended to follow up with either a Western Blot Test or an IFA test.
If your cat has tested positive for FIV but you are not sure if it has had the vaccine or want to be sure it does/doesn't have the virus then you may be able to request a PCR (polymerase chain reaction) test, which will be able to detect the presence of FIV DNA in the blood.
How is FIV treated?
There is no cure for FIV, once a cat has it, it is for life. The goal is to provide supportive care to the infected cat. This may include:
- Regular veterinary check ups.
- Maintaining proper parasite control.
- Ensuring that prompt veterinary attention is sought at the first sign of illness.
- Feed a high-quality diet.
- Limiting their exposure to disease by keeping them indoors and away from the neighbourhood or stray cats.
- The use of antibacterial and antifungal drugs where recommended.
- Maintain a proper vaccination regimen to protect your cat from other infectious diseases.
- Blood transfusions may be necessary for stage 3.
- High-calorie supplements may be necessary for stage 3.
- There are other drugs available such as interferon and AZT which have been used in some cats, but it is best to speak to your veterinarian about these.
Should I have my FIV positive cat euthanised?
No, this isn't necessary. FIV positive cats can live for many years, especially if they are given prompt medical attention when necessary and supportive care.
Preventing FIV in cats:
Desexing of all pets, not allowing them to free roam and testing all cats used for breeding.
There is now an FIV vaccine which is available, it isn't 100% effective. Cats given the vaccine will test positive for FIV which may result in confusion, especially in the case of a cat being picked up by a shelter or council. For further information on the vaccine, read here...
Which cats are most at risk of FIV?
Un-neutered, free-roaming males are at the greatest risk of FIV. Any cat allowed to free roam is at risk of catching FIV.
Can FIV positive and FIV negative cats live in the same household?
The general opinion is yes, this is okay as long as there isn't any fighting between the cats. As FIV positive cats are more susceptible to opportunistic infections it is important to ensure the health and vaccination status of ALL cats in the household.
Others suggest either keeping FIV positive cats isolated from FIV negative cats or rehoming the FIV positive cat in a single cat household. Your veterinarian is the best person to speak to in this regard.
Can I catch FIV from my cat?
No, it is not possible to catch FIV from your cat, nor is it possible for your cat to catch HIV from a human. While both viruses come from the same family, they are species specific.