Feline immunodeficiency virus (FIV) is a virus that eventually causes immunosuppression in cats – it interferes with a cat’s immune system response. This means that, eventually, an FIV+ cat will be more susceptible to disease than an FIV- cat; the positive cat will have a harder time fighting off infection since its immune system is weakened. Once infected, there is no cure. There are over 80 different strains of FIV. It is species-specific; people and other animals cannot catch FIV.
With good care, many FIV+ cats can live nearly normal lifespans; it’s not uncommon to find FIV+ cats over 10-15 years of age.
What happens to a cat with FIV?
There are 3 stages of FIV infection:
This occurs 4-6 weeks after the initial infection. The cat may get a mild fever for a few days, swollen lymph nodes (lasting several days to weeks), and decreased white blood cell count. There may be some anemia or diarrhea. Then these symptoms go away, and the cat enters the second stage:
In the latent stage, there are no symptoms, although the cat tests FIV+. This stage can last for years. In fact, many cats die of other causes before the chronic stage develops.
The chronic stage is where the cat’s immune system can’t effectively fight off infection. FIV interferes with a type of white blood cell called the T-helper cell. Over time the immune system is depressed. Later, lymph nodes are affected and all types of white blood cells are suppressed. This leads to chronic inflammation and infection.
Mouth infections are characteristic: gingivitis (gum inflammation), stomatitis (inflammation of the mouth lining), and periodontitis (inflammation of the tissue around teeth). Other infections can include upper respiratory, skin, intestinal tract, intermittent fever, abscesses, chronic sinusitis, and, more rarely, neurologic dysfunction and tumors.
There may be cycles of infection; a cat may have periodic bouts of say, sinusitis that go away with treatment. The cat may then be in good health for a period of time, and then get the sinusitis again.
How is FIV spread?
FIV is present in blood, saliva, and cerebrospinal fluid of infected cats. FIV is relatively hard to spread. The main route of transmission is bite wounds, where there is blood and saliva exchange. FIV does not survive outside the cat’s body and is only very rarely spread by casual cat to cat contact. Female FIV+ cats can pass FIV to their kittens.
The cat at greatest risk is an unneutered, outdoor male – he’ll tend to roam, fight and mate, getting and giving bite wounds.
How do you know if a cat has FIV?
The blood test detects antibodies against the virus. FIV is in the family of lentiviruses, and these viruses persist once a cat is infected – they don’t go away. So the presence of FIV antibodies shows infection.
There are 3 basic tests for FIV:
ELISA (enzyme-linked immunosorbent assay)
IFA (indirect immunofluorescent antibody assay)
The ELISA test can have some false positives (i.e. a cat’s test result is FIV+ while the cat is FIV-). More false positives occur in low risk groups. You can redo the ELISA test in several weeks, or confirm with the more antibody specific IFA or Western Blot, which rarely have false positives.
There can also be false negative results. It may take 8-12 weeks after infection for a cat to test FIV+. A negative test can be repeated in 3-4 months to confirm it is a true negative. A small percentage of FIV+ cats may test negative since they have too little antibody to detect; mostly these would be cats far along in the chronic stage.
Kittens get antibodies to many diseases, in the mother’s milk. Kittens younger than 6 months may have FIV antibodies gotten from the mother, without having FIV themselves. So, if kittens test FIV+, you can retest after 12 weeks of age, if need be doing a final test after 6 months of age. Many kittens initially testing FIV+ will test FIV- after they clear their maternal antibodies.
Care of your FIV+ cat
You can support an FIV+ cat through a long life. Of course, keep the cat strictly indoors to limit exposure to infection. Get regular vaccinations, as long as the cat is in the latent stage. Check with your vet about vaccinations for a cat who is symptomatic. Good diet, including vitamin supplements such as buffered vitamin C (sodium ascorbate) and vitamin E, builds immune system strength.
When you see any signs of illness, go to the vet – early treatment can head off many problems. Antibiotics can control infection; chronic stage cats may cycle on and off antibiotics. For a cat in the chronic stage, the relatively inexpensive drug alpha interferon can help stimulate the immune system. Finally, love is a powerful immune system enhancer – don’t forget to cherish your FIV+ cat.