CAT DISEASES
FELINE IMMUNODEFICIENCY VIRUS 
The Feline Immunodeficiency Virus (FIV) is also called the Feline AIDS and the Kitty AIDS Virus. It is linked to the AIDS virus that affects humans because of the similarities in the two diseases that result. However, the FIV and the human AIDS virus affect only one species; the AIDS virus affects only humans and the FIV affects only cats.
The FIV is transmitted primarily by catfights via biting. Other interactions of cats, such as eating or drinking from common bowls, or grooming each other, have not been shown to be significant in transmission.
The presence of the FIV can be detected by a simple blood test. A positive means the cat is infected with the virus and likely will be infected for the remainder of its life. A negative may mean the cat is not infected. However, false negative occur in two situations:
- From the time of virus inoculation in the cat, it takes up to two years for the test to turn positive. Therefore for up to two years the test will be negative even though the virus is present in the cat.
- When the cat becomes terminally ill, the test may again turn negative. This occurs because the antibodies produced by the cat (that are detected by the test) become attached to the large amount of virus present; they are not available to react in the test.
The FIV infected cat will generally go through a prolonged period of viral dormancy before it becomes ill. This incubation period may last as long as 6 years. Thus, we generally do not diagnosis on FIV sick cat at an early age.
When illness occurs, it takes the form of various severe chronic illnesses. Absences that should heal within a week or two may remain active for several months. Respiratory infections may linger for weeks. The cat may lose weight and go through periods of not eating well; the hair coat may become unkempt. The cat may have episodes of treatment-resistant diarrhea. Ultimately, widespread organ failure occurs and the cat dies.
There is no treatment that will kill the FIV. Sometimes the disease state can be treated and the cat goes through a period of recovery and relatively good health. However, the virus will still be in the cat and will become active at a later date. Therefore, the long-term prognosis is not good.
If you have a cat that tests FIV positive but is not ill, it is not necessary to immediately euthanatize it. As long as it does not fight with your other cats or those of your neighbors, transmission is not likely to occur. However, if it is prone to fight or if another cat often instigates fights with it, transmission is likely. In fairness to your neighbors we recommend that you confine a FIV cat to your house so the likelihood of transmission is minimized.
Feline Leukemia Virus Diseases
Feline Leukemia was, until recently, the most common fatal disease of cats. Because we can now protect cats with leukemia vaccine, we are seeing fewer cases of the disease. However, it still remains a major cause of death in cats.
‘Leukemia’ means cancer of the blood. This was the first disease associated with the Feline Leukemia Virus (FeLV) and thus the source of its name. However, this virus causes many other fatal diseases in addition to leukemia. Because the virus is called the Feline Leukemia Virus, we often use the term ‘leukemia’ rather loosely to include all of the diseases associated with the virus, even though many are not cancer of the blood.
THE DISEASES
There are three major disease categories associated with the FeLV: 1) The Leukemias are cancers of the blood cells. 2) Lymphoarcoma (LSA) is cancer of many internal organs involving lymphoid tissue. These organs include the lymph nodes, intestinal tract, kidneys, liver, spinal cord, and brain. Actually, almost tissues can be affected. 3) The Non-Cancerous Diseases include a variety of somewhat unrelated diseases. Anemias, abortions, arthritis, and immune suppression are examples. When the immune system is suppressed, the cat becomes susceptible to many diseases it would ordinarily resist and mild, common diseases, such as respiratory infections, may become fatal.
TRANSMISSION
The main means of transmission of the FeLV is trough cat fights. Because large quantities of the FeLV are in the cat’s saliva, the puncture wounds associated with fighting result in injections of the virus into the cat. Other means of infections include common food and water bowls, cats grooming each other, and from mother to kittens before birth. Even though a cat may be exposed to the virus, its immune system may respond to the virus infection and protect the cat. About 30 – 40% of adult cats exposed to the virus will become persistently infected. Young kittens have a much higher infection rate.
LEUKEMIA TESTING
The ‘leukemia test’ is actually a test to determine if the virus is in the cat. The interval of time between the virus infecting the cat and the development of disease may be up to 4 years. During that time the cat will be absolutely normal, but the test will be positive.
If the test is run within the first four weeks of exposure to the virus, it may detect a transient time when the cat’s immune system is battling the virus. If the immune system is victorious, the virus will be overthrown, and the test will turn negative again. If there is a chance of that occurring in your cat, we will suggest another test.
There are two intermediate forms of FeLV infections that result in complicated, and often confusing, laboratory test results. These are known as the latent infection and the immune carrier state. They will be discussed with you if they are appropriate to your cat’s situation.
There are a few types of lymphosarcoma process, and is then rejected from the body. Diagnosing these types of LSA will require more tests than normal.
TREATMENT
Some forms of leukemia are totally nontreatable. Others may respond to chemotherapy. However, even most of the responsive ones have an average survival time of less than one year. Because the virus is not affected by treatment, the cat will always remain infected. This means relapse is possible (and expected), and the cat will remain contagious to other cats. These factors cause us to recommend treatment in very few situations.
DISINFECTION
The FeLV lives only a few minutes to a few hours outside the cat if the environment is dry. Therefore, extensive environmental disinfection is not necessary. If you wait even 2 days to get a new cat, you can be assured that none of the virus from a previous cat will remain in your home.
THE FeLV INFECTED, NORMAL CAT
The cat is completely healthy and may remain so for several years. However, it is also contagious and dangerous to other cats. If you have a cat like this, it should be isolated from non-infected cats to prevent contagion. Many people find this undesirable or impossible and elect euthanasia to protect non-infected cats, theirs and those of their neighbors.
HUMAN HAZARD
Extensive tests have been conducted for over 15 years to determine if the FeLV can be transmitted to humans. Thus far, no conclusive evidence has shown any form of contagion to humans or other animal species, including the dog. However, persons with compromised immune systems are of concern to many researchers and to us. Newborn babies, persons on chemotherapy, or transpiant recipients on air-rejection drugs probably should not be unnecessarily exposed to this or any other virus.
PREVENTION
A vaccine is available to protect cats from the FeLV. Although not 100 % of cats are totally protected, the vaccine is strongly recommended for cats that are exposed to open populations of cats, i.e., outdoor cats. We have definitely seen a decline in the incidence of feline leukemia since the vaccine became in widespread use. We firmly recommend it. If your cat stays indoors all the time and is not in contact with another cat that goes outdoors, its need for the vaccine is minimal.
Cats that are already infected with the FeLV will not be helped by the vaccine. (They will not be hurt by it, either.) We recommend pre-vaccination testing for the FeLV for 1) cats that have a history of cat fights of fight wounds i.e. abscesses, 2) cats exposed to FeLV-infected cats, 3) cats from unknown backgrounds, especially from animal shelters, humane societies, or pet shops, and 4) your cat if you want it done for whatever reason.