The feline immunodeficiency virus, also known as FIV, is the virus which causes the disease known as AIDS in cats. The virus itself is classified as a lentivirus and is in the retrovirus family, as is the feline leukemia virus (FeLV). However, the feline leukemia virus and the feline immunodeficiency virus are two distinctly different viruses and, though the diseases that they cause are similar in some ways, they are different in others, including the way the viruses are passed from one cat to another.
Infection with the Feline Immunodeficiency Virus (FIV)
The most common method of spread for the feline immunodeficiency virus is through bite wounds sustained during cat fights. FIV is not easily spread through direct casual contact which occurs in a non-aggressive manner, such as grooming or sharing litter boxes, food bowls, toys and other shared objects.
Rarely, FIV has been passed from an infected mother cat to her kittens, either when the kittens pass through the birth canal or when they ingest FIV-infected milk from the mother cat. Sexual contact is also not considered to be a major method of infection with feline immunodeficiency virus but has been known to occur. Blood transfusions from improperly screened cats can also cause infection with the feline AIDS virus.
Symptoms of AIDS in Cats
Once infected with the feline immunodeficiency virus (FIV), the virus is transported to local lymph nodes where it infects and multiplies in T-lymphocytes (a type of white blood cell important to the feline immune system). The feline AIDS virus then spreads to the other lymph nodes found throughout the body. The infection is usually asymptomatic in the early stages but eventually causes suppression of the feline immune system. The resulting immune deficiency makes the cat susceptible to secondary infections with opportunistic bacteria, viruses, fungi and protozoans that would not be problematic for a healthy cat with a normal strong immune system.
Symptoms which may be seen in cats with feline AIDS are variable and include:
- slow progressive weight loss that may progress to a wasting disease later in the course of disease
- lack of appetite accompanied with a persistent fever and (sometimes) a poor hair coat
- persistent diarrhea
- eye lesions (uveitis)
- stomatitis and/or gingivitis
- chronic and/or recurrent infections of the urinary tract, skin or upper respiratory tract
- cancer (various forms)
- blood diseases affecting the white blood cells or red blood cells
- abortion of unborn fetuses, stillborn kittens
- seizure, behavioral changes and other neurological disorders
Diagnosis of Feline AIDS or Infection with FIV
Infection with feline immunodeficiency virus is usually diagnosed by a blood test that detects antibody to the virus. Most commonly, ELISA (enzyme-linked-immunosorbent serologic assay) testing is used as a screening test for FIV. If a positive ELISA test for FIV occurs, a second test known as the Western Blot is usually recommended to confirm infection and rule out the possibility of a false-positive ELISA test result.
Kittens less than 6 months of age may inherit antibodies from an infected mother cat. These kittens may experience a false-positive FIV test due to the maternal antibodies present but may not actually be infected or even likely to become infected with the virus. For kittens less than 6 months of age, repeated testing every 2 months is recommended until the kitten is 6 months or older to determine the true FIV status.
Newly infected cats may require a period of 8-12 weeks to develop an antibody level that is detectable on blood tests. Therefore, early in the infection, feline immunodeficiency virus testing may be falsely negative. In addition, cats in the later stages of feline AIDS may have false negative test results for FIV because their immune systems may become compromised to the point of being unable to produce detectable levels of antibody.
Additionally, cats vaccinated with the feline immundeficiency virus vaccine currently available will have positive blood tests with both the ELISA and the Western Blot tests. These results are currently indistinguishable from test results in a cat that is truly infected with FIV.
Feline immunodeficiency virus, or FIV, causes feline AIDS. AIDS in cats is a disease which is commonly misunderstood. While the virus is similar in many ways to the human AIDS virus (HIV, human immunodeficiency virus), feline AIDS is not contagious to people. Cats with positive tests for FIV can lead long lives when living under protected conditions.
Join the Conversation