Feline Immunodeficiency Virus
The feline immunodeficiency virus (FIV) is a retrovirus that is transmitted from cat to cat via direct inoculation. It is often referred to as a disease of unfriendly cats because bite wounds are the most common mode of transmission. Infection is for life as there is not cure. The virus can cause acute disease but many cats remain asymptomatic and healthy for years after infection.
The virus is spread most commonly by bite wounds and as a result intact male cats are most prone to infection. Outdoor cats are also at higher risk than indoor cats in stable populations. There appears to be wide variability in the ability of queens to pass the virus on to kittens though the placenta or milk depending on the mothers immunity, blood levels of virus and the strain of the virus.
Clinical signs after initial infection may include fever, low blood cell counts, and infection though this phase often goes unnoticed. Most infected cats are asymptomatic carries who will not show signs of illness for months to many years after infection.
Because the virus suppresses the immune system, infected cats are susceptible to secondary infections and cancer. It is complications of these secondary diseases that tend to be most problematic. These can include chronic skin disease, gastrointestinal disease, respiratory disease and dental disease (gingivitis, stomatitis, periodontitis). These cats may also have recurrent eye problems.
Diagnosis is by an antibody test called a serum ELISA test. This test looks for antibodies produced in response to the virus and can be quickly performed at most veterinary hospitals. While these tests are very reliable, a positive test needs to be confirmed with a Western Blot assay that can be run at most commercial laboratories. Cats that should be tested include any new cat or kitten prior to introducing into the household, any sick cat or any at risk cat (outdoors, fights). It is important to note that FIV antibodies are passed from mother to kittens and they will persist for up to 6 months. Therefore any positive test on a kitten under 6 months of age needs to be repeated after 6 months as the test will likely be negative after antibodies clear. The FIV vaccine will also interfere with testing as it will cause a positive antibody response. There is currently no way to differentiate an infected cat from a vaccinated cat.
Treatment for infected cats is supportive and involves environmental management as well. These cats do best when kept strictly indoors in a stable house hold. This prevents them from spreading the disease to cats outside, prevents fighting in the house and decreases these cats exposure to other infectious diseases. Routine dental care needed to help keep the mouth healthy and prevent serious periodontal infection. Any type of infection (urinary, respiratory, skin, dental, etc.) needs to be treated aggressively - more so than with an uninfected cat. These cats need to be examined every 6 months with full lab work and urinalysis every 6-12 months with the goal being to catch any problems early. They need year round flea and heartworm prevention and regular dewormings as well. These cats should also be spayed or neutered.