The feline immunodeficiency virus (FIV) infection is a complex retrovirus that causes immunodeficiency disease in domestic cats. Immunodeficiency is the medical term used to describe the body’s inability to develop a normal immune response. FIV is slow moving, capable of lying dormant in the body before causing symptoms (lentivirus). It is in the same class of viruses as the human immunodeficiency virus (HIV), the causative agent of acquired immunodeficiency syndrome (AIDS) in people.
There is no genetic susceptibility for infection, although genetics may play a role in the progression and severity of the disease. The average age is five years at the time of diagnosis, and the likelihood of infection increases with age. FIV is a transmissible disease that occurs more often in males because of their tendency to be more aggressive, and because they are more likely to roam, thereby increasing their exposure to the virus.
- Diverse symptoms owing to the decreased ability to develop a normal immune response. Associated immunodeficiencies cannot be distinguished clinically from feline leukemia virus (FeLV)
- Recurrent minor illnesses, especially with upper respiratory and gastrointestinal signs
- Mild to moderately enlarged lymph nodes
- Inflammation of the gums of the mouth and/or the tissues surrounding and supporting the teeth is seen in 25 percent to 50 percent of cases
- Upper respiratory tract disease is seen in 30 percent of cases - inflammation of the nose; inflammation of the moist tissues of the eye; inflammation of the cornea (the clear part of the eye, located in the front of the eyeball); often associated with feline herpes virus and calicivirus infections
- Eye disease - inflammation of the front part of the eye, including the iris; disease of the eye in which the pressure within the eye is increased (glaucoma)
- Long-term (chronic) kidney insufficiency
- Persistent diarrhea seen in 10 percent to 20 percent of cases
- Long-term, nonresponsive, or recurrent infections of the external ear and skin resulting from bacterial or fungal infections
- Fever and wasting - especially in later stage
- Cancer (such as lymphoma, a type of cancer that develops from lymphoid tissue, including lymphocytes, a type of white-blood cell formed in lymphatic tissues throughout the body)
- Nervous system abnormalities - disruption of normal sleep patterns; behavioral changes (such as pacing and aggression); changes in vision and hearing; disorders usually affecting the nerves in the legs and paws.
- Cat-to-cat transmission; usually through bite wounds and scratches
- Occasional transmission of the virus at the time of birth
- Sexual transmission is uncommon, although FIV has been detected in semen
Your veterinarian will perform a thorough physical exam on your cat, taking into account the background history of symptoms and possible incidents that might have precipitated this condition. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. Your doctor will need to rule out bacterial, viral, or fungal infections, and will also test for parasites and tumors before settling on a final diagnosis.
Unless your cat is severely dehydrated, it will be treated on an outpatient basis. Your veterinarian will first work to manage any secondary infections. While secondary infections will not usually cause disease, your cat’s weakened immune system will given them entrée and they will cause further complications in your cat’s overall health. Surgery may be necessary for dealing with infected teeth and for the removal of tumors. A special diet plan may also need to be put into place.
LIVING AND MANAGEMENT
How much monitoring your cat will need from you depends on secondary infections and other manifestations of the disease. You will need to watch for the occurrence of infections in your sick cat, and be aware that wasting may occur, and that your pet may die of this disease. But, in general, the earlier FIV is detected, the better your cat’s chances are for living a long and relatively healthy life.
Within 4.5 to 6 years after the time of infections, about 20 percent of cats die; however, over 50 percent will remain without clinical signs of the disease. In the late stages of the disease, when wasting and frequent infections are most likely to occur, life expectancy is less than a year. Inflammation of the gums and mouth may not respond to treatment or may be difficult to treat.
In order to prevent this disease from occurring in the first place, you should vaccinate your cat against the virus, and protect your cat from coming into contact with cats that are FIV positive. You will also want toquarantine and test new cats that are coming into your household until you are sure that they are free of the virus. It is important to note that some cats will test positive for FIV if they are carriers, although they may never have symptoms of the virus, and that cats that have been vaccinated against the virus will test positive for it even though they do not carry it. Euthanasia is not normally called for when a cat has tested positive in part because of these reasons. If your cat has tested positive you will need to talk to your veterinarian about what to do to prevent possible transmission to other cats, and what symptoms to be watchful for, should they occur.
UPDATE Information: Feline Immunodeficiency Virus: Does it Really Cause Disease? (AVMA Conference, 2014)