by Cherry Mattias, DVM
The questions we ask during every feline examination in our feline-only practice are “When was the last time your cat was tested for FELV/FIV?” and “What was the result?” It is necessary to know this status in order to optimize the care and management our patient’s health. The alphabet soup of feline disease can be confusing for the client. In this series of articles I will attempt to explain the reasons for testing. I will start with the two most common, life-threatening infectious diseases. I will explain certain terms as I go along in an attempt to make things clear.
Cats are susceptible to multiple kinds of infectious diseases. Infectious means caused by a live organism such as a virus, bacteria, or a parasite. Infectious is not the same as contagious. A contagious disease is passed from one cat to another. An infectious disease may or may not be contagious and may or may not be life threatening. An example of a non-life-threatening, contagious, infectious disease is Ringworm. Two contagious, infectious, life-threatening diseases are Feline Leukemia (FELV) and Feline Immunodeficiency Virus (FIV). There are others, including Feline Infectious Peritonitis (FIP) and Feline Panleukopenia (FPV). Today’s article will address FELV and FIV. These are very common in cats. So common, in fact, that The American Association of Feline Practitioners (AAFP) has established guidelines for management and testing for FELV and FIV.
Feline Leukemia (FELV) is a viral disease. It is shed primarily in the cat’s saliva. Other body secretions such as nasal discharge, feces, milk, and urine can also carry the virus. Close, moist contact is the typical way in which cats infect each other. Cats transmit the disease by grooming each other, eating out of the same bowls, sneezing, or sharing litter boxes. We say that cats that like each other spread this disease. However, cat bite abscesses and oral inflammation are two conditions associated with a very high rate of infection. Cats who are sick with FELV develop anemia, secondary opportunistic infections, cancer, eye problems, and blood disorders. They can eventually die from complications brought on by the damage the virus does to the immune system and bone marrow.
Once the virus enters the body it goes through the tissue in phases. The cat can put up an immune response in the tissues. The disease may or may not progress. To further complicate matters, their test results do not always indicate the true status of the disease.
If we exposed 100 cats to the FELV virus, they will not all develop the disease. About 30 would put up a strong immune response. These cats test positive and later negative. Another 30 would become sick within the first year after exposure. The virus causes suppression of the immune system allowing other diseases to make the cat very ill.
Many times the cat dies within the first year of exposure. These cats test positive. Another 40 cats would become latent carriers, the virus hiding in the cat’s genome. This is a transient condition lasting about 30 months. These cats test negative. One cat out of 100 is an immune carrier or presents with an atypical infection. Atypical means it does not show itself in the normal way in the cat’s body. The virus can be in the mammary glands, the eye, or the urinary bladder. These cats can be a weak, positive, or have discordant results for two tests. Discordant means the results between the two tests do not agree. Queens may pass the virus to their kittens without being positive themselves. The complexity of the way the virus acts in different cats is the reason we DO NOT EUTHANIZE cats that initially test positive for FELV, unless they are very ill. They are re-tested with the same test later, or a different type of test.
There are several types of tests for FELV and FIV. The in-hospital test is called an ELISA and takes about 15 minutes. If the test results are positive, it should be verified with a different type of test called an IFA. Keep in mind that no test is 100% accurate. This is another reason we do not euthanize the cat just because his test is positive. If two types of tests agree and they are positive, then a discussion about management and treatment of a positive cat should take place between client and Veterinarian. These tests verify infection only, not necessarily clinical disease. Clinical means the cat is showing signs of illness. It is possible for a healthy positive cat to live for years.
Which cats should be tested? All sick cats regardless of previous test results or vaccination; cats to be adopted or new in the household; cats at risk of exposure (cats with abscesses); cats with an unknown status; cats about to be vaccinated.
So what is the good news? We have an excellent vaccine for this disease. So test and vaccinate!
Feline Immunodeficiency Virus (FIV) is the other common, life-threatening, contagious, disease that is also caused by a retro virus. This disease is more likely spread by cat bites. We say that cats that don’t like each other (fighting) spread this disease. However, recent evidence has shown that cats who reside with each other, in close proximity for a long period, can transmit the disease. It is similar to human AIDS, although not transmissible to humans. Cats that are sick with FIV have a compromised immune system. They’re unable to marshal defenses against disease and have a difficult time healing from wounds. They often have diarrhea, fever and depression. Their mouths become infected (stomatitis). In later stages they may have chronic respiratory or skin diseases.
There is an in-hospital ELISA test for FIV. It is almost always tested for at the same time as FELV. Kittens that test positive for FIV should be tested again after six months of age, as maternal antibodies can produce a positive result. Vaccination can also give a positive result. The vaccine for this disease is only used under special circumstances. Whether or not to use this vaccine should be discussed with your veterinarian. Another test called a Polymerase Chain Reaction Assay (PCR) may be able to discern between an infected cat and a vaccinated cat.
FELV and FIV positive cats can live a long time with good veterinary care. They may succumb to causes which have nothing to do with their FELV/FIV status. I often see old Toms, males that have not been neutered, come into the office with horrible wounds from fighting that have not healed. Their mouths are usually very inflamed, their skin is scabby, and their fur is scraggly. They almost always test positive for FELV or FIV.
These two diseases are life threatening and very contagious. The vaccine for FELV is safe and very effective. Knowing your cat’s status is the first step to protect him or her from being exposed to and dying from these diseases. Healthy positive cats can live a good life but require diligent monitoring and good care.
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