FIV or Feline AIDS in Cats

The primary means of infection is through a deep bite wound. For this reason, the virus is more common in outdoor cats and aggressive males. Elderly cats are also more likely to be infected. It is estimated that one and a half to three percent of all healthy cats in the United States have FIV infections. In cats that are sick, the infection rate is closer to fifteen percent.

Vaccines are available to prevent FIV but they have not been proven to be effective against all strains of the virus. The key to preventing the spread of FIV infection is early diagnosis and prevention of contact between infected and uninfected cats. Feline immunodeficiency virus can only be spread between cats and cannot infect humans.

Feline immunodeficiency virus (FIV), also called Feline AIDS, is a virus similar to leukemia (FeLV). Both are classified as lentivirus, or “slow virus," meaning that after the initial infection it can lay dormant for months or years before additional symptoms begin to show. The virus attacks the immune system, increasing risk of contracting secondary infections and medical conditions such as various types of cancer. The combination of opportunistic illness and compromised immune function is often deadly. 

In the early stages of infection, cats will likely experience enlarged lymph nodes and fever. This may go unnoticed if the animal is otherwise healthy. After recovery, the cat may have no symptoms for several months or years. Eventually the immunodeficiency progresses and one or more of the following symptoms emerge:

• Inflammation of the gums or mucous membranes inside the mouth
• Inflammation of uveitis (inner layer of the eye)
• Discharge from eyes or nose
• Anemia
• Low white blood cell count
• Poor coat condition
• Cancer 
• Blood diseases
• Chronic skin infections
• Gastrointestinal upset
• Chronic diarrhea
• Urinary or bladder system problems
• Respiratory tract infections
• Neurologic disorders or seizures
• Behavior change
• Spontaneous abortion in females
• Poor appetite
• Weight loss
• Wounds that won’t heal
• Frequent illnesses followed by periods of relative health

Bite wounds caused by fighting is the number one cause of FIV infection. Occasionally, an infected mother can pass the virus to kittens during childbirth or through nursing. The infection is not spread through casual contact like grooming, sneezing, or the sharing of dishes or litter boxes. Although the virus has been found in semen, it is not likely to be spread through sexual contact.

All unvaccinated cats should regularly be tested for FIV infection. The condition is diagnosed when a blood test indicates the presence of antiviral antibodies. Cats that have previously been vaccinated will not benefit from the test as it is impossible to determine whether the antibodies were produced at the time of the vaccine or following an infection. There is no commercially available test for vaccinated cats. When a test has been performed, retesting after a period of several weeks or months is almost always recommended. There is a possibility of false-positive results, and false-negatives may occur when the body has not produced enough antibodies to register.

In addition to blood tests, the veterinarian will review the cat’s full medical history, examine it for clinical symptoms, and consider whether the cat has been previously vaccinated. Owners should discuss all possible symptoms with the vet, even if they seem unimportant. This could be critical to proper diagnosis and treatment.

There is no cure for FIV and little evidence exists regarding the effectiveness of antiviral or other alternative treatments. Care will be supportive, with a focus on lengthening the period of time between illnesses and improving the overall quality of life for the cat. If the cat’s health has not been severely compromised due to frequent or severe illnesses, outlook is generally positive for several months or years. If weight loss and persistent fever are present, prognosis may be guarded or negative.

Hospitalization is usually not required unless the cat is severely dehydrated. Treatment recommendations will depend on the secondary infections or other medical conditions that are present. The veterinarian may prescribe antibiotics and anti-inflammatories and may recommend fluid and electrolyte replacement therapy. If tumors are present, removal may be recommended. 

Infected cats should be examined by a veterinarian every six months. Closely monitoring the condition of the cat's eyes, skin, gums, lymph nodes, and weight will help to proactively diagnose and treat secondary conditions as they arise. A series of standard lab tests should be performed annually.

To avoid the spread of infection, cats with FIV should be kept indoors and away from other cats. They should also be spayed or neutered as soon as their health allows. A quiet, stress-free environment will provide the best opportunity for healing. Cats should be fed a healthy, balanced diet and the ingestion of raw meat, raw eggs, or unpasteurized dairy products should be avoided. If cats display a change in behavior or other unusual symptoms, a prompt veterinary consultation is recommended.