Cat Owners: Update on Feline Immunodeficiency Virus (FIV)

When the disease was first discovered in 1986 we thought that this second viral disease to cause suppression of the feline immune system (Feline Leukemia Virus, FeLV, was discovered in 1964) was going to explain many severe, untreatable disease symptoms in cats who were leukemia test negative. Associations between FIV and chronic diarrhea, oral inflammatory diseases, and other non-responsive conditions were initially thought to be very common and almost indicative of the disease. However, over time we have come to understand much more about the transmission and prognosis of this viral disease and how it can be successfully managed in our cat owning clients’ homes.

Between 1 and 13 percent of all domestic cats are infected with the FIV virus. The wide range is due to the fact that there can be regional clusters of infected cats – probably related to the size of the feral cat population. Since the primary way the virus is transmitted is through bite wounds, un-neutered more territorially aggressive feral cats would be at greatest risk. Therefore, neutered and spayed indoor cats are at the least risk, with indoor/outdoor neutered cats falling somewhere in between. Casual contact between housemates, probably including social grooming and sharing food bowls, is not suspected to be an efficient route of spreading FIV but because active research on FIV transmission is in progress, we never say that house mates are at zero risk. In contrast, social grooming, as well as bites are considered to play a role in spreading Feline Leukemia Virus.

Although early infection with FIV can result in transient fever and mild lymph node enlargement, most cats soon enter a subclinical stage that can last for months to many years. Eventually, for reasons that are not well understood, the cats with “hidden” infection lose the immune system’s ability to suppress the replication (reproduction) of FIV and the virus spreads through the blood stream allowing increased susceptibility to infections and opportunistic diseases. The most common conditions secondary to FIV infection are:

The most common conditions secondary to FIV infection are

  • Poor coat and persistent fever with appetite loss
  • Inflammation of gums and mouth
  • Recurring infections, including upper respiratory virus and bladder
  • Persistent diarrhea and a variety of eye conditions
  • Progressive weight loss leading to severe wasting late
  • Various cancers and blood diseases much more common
  • Abortion of kittens and reproductive failure
  • Neurologic disease including seizures and behavioral changes

We do recommend that FIV positive cats be examined regularly and weighed regularly, since weight loss can be an early symptom of secondary disease.

We also recommend blood testing for FIV and FeLV for all previously untested cats, new cats brought into the household, and because there can be an incubation period of up to three months for cats “off the street”, a retest of new cats in three months is prudent. Also any ill cats who could have had exposure (ie., sometimes sneaking outside) should be retested. If you find that a member of your multi-cat household is FIV positive, the other cats should be tested. In an ideal world, all positive cats should be separated out, especially if there is fighting or rough play among them. If this is impossible, and there is no fighting, including clawing, then the risk to non-infected cats appears to be low. Many studies have shown there is no risk to humans from exposure to FIV.

FIV-infected cats must be kept indoors to prevent spread of the disease and to prevent them from exposure to infectious/parasitic organisms from hunting and eating the prey. By the same token, no raw or undercooked foods should be given to them because of their compromised immune systems.

Keeping cats indoors and away from potentially infected cats (like feral cats being fed on the back porch) is the best plan for FIV prevention. There has been a vaccine developed against FIV, but unlike the FeLV vaccine, the current FIV vaccine will create a positive result on the FIV screening test used by shelters and veterinarians. The fear that a vaccination would make a run-away house cat test FIV positive at the shelter and possibly be euthanized has prevented most veterinarians from recommending this vaccine.

Identifying cats with FIV, managing them properly, and maintaining a regular preventive health program including regular examinations with our veterinarians has been shown to allow many infected cats to live a long, happy life as a pet in your house.

Pittsburgh Spay & Vaccination Clinic is a state-of-the-art, full-service suburban veterinary facility serving the Pittsburgh Area since 1980.. We offer diagnostic, medical, surgical, and dental care to dogs, cats, ferrets, rabbits, and pocket pets in the Pittsburgh area.

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