ALL CREATURES ANIMAL CLINIC, LTD.
Mark Hale, DVM
FELINE LEUKEMIA VIRUS
WHAT IS FELINE LEUKEMIA VIRUS (FeLV)?
Feline leukemia virus is a contagious virus that causes many different forms of cancer in cats.
HOW IS THE VIRUS TRANSMITTED?
When a susceptible cat comes in contact with an infected cat or its contaminated saliva, urine, or feces (stools), infection may result.
HOW DOES THE DISEASE DEVELOP?
Very few cats die as a result of the initial infection. Some cats fight off the virus and become immune to it. Other cats show mild signs of illness and recover. These cats continue to carry the virus in their bodies and may, weeks or years later, show signs of a form of FeLV cancer. In addition, these cats may show signs of diseases common in cats carrying FeLV but not directly caused by the virus.
HOW IS IT DIAGNOSED?
Diagnosis is based on blood tests specific for FeLV infection. In an apparently healthy animal, results are carefully interpreted to determine whether the pet is susceptible to infection, presently infected, or is recovering from a previous infection. Sometimes the tests are repeated weeks or months later.
The same tests are used to diagnose FeLV infection in a sick animal. Results of other blood tests, radiographs (x-rays), a thorough physical examination, and the cat's history help determine whether FeLV, cancer or a related disease is present.
WHAT ARE SOME OF THE DIFFERENT FORMS OF NEOPLASIA (CANCER) CAUSED BY FeLV?
Tumors (lymphosarcomas and fibrosarcomas) and many kinds of leukemia (disorders of the white blood cells) are caused by FeLV. FeLV causes anemia, a harmful decrease in the number of red blood cells or hemoglobin. Hemoglobin is the oxygen-carrying protein these cells contain. Other abnormalities of the blood and lymph system, neurologic (related to the nervous system), reproductive problems (stillbirth, abortion, etc.) and kidney disease are also linked to FeLV infection.
WHAT DISEASES ARE RELATED TO BUT NOT DIRECTLY CAUSED BY FeLV?
Feline infectious peritonitis, chronic respiratory infections, poor healing of abscesses (localized collections of pus),Toxoplasma, and Hemobartonella (parasites) infections are some of the diseases related to FeLV infection.
WHAT ARE THE SIGNS OF FeLV INFECTION?
Because FeLV can cause so many different types of cancer and other diseases, the signs are many and varied. Sometimes no signs are apparent. Often, an affected cat shows long-term depression and lack of appetite. Vomiting and diarrhea may occur if an abnormal tumor is present.
WHAT IS THE TREATMENT FOR FeLV DISEASE COMPLEX AND RELATED DISEASES?
Patients with related diseases not directly caused by FeLV can be treated. However, the presence of the virus depresses the body's natural immunity, and the response to treatment may be poor.
No known cure exists for cancer caused by FeLV. In certain cases, treatment may be given in an attempt to bring about remission of the disease. If treatment is not a reasonable alternative, euthanasia (putting an animal to sleep) is recommended to end the suffering of the afflicted animal.
WHAT SHOULD BE DONE ABOUT A CAT THAT IS CARRYING THE VIRUS BUT SEEMS HEALTHY?
A cat that carries FeLV can spread infection to other cats. It should be kept indoors and not allowed to come into contact with other cats. The decision to euthanize an animal known to carry FeLV is extremely difficult. The newest information on FeLV infection, the attitude of those involved, and the possibility of a healthy life for the cat should be considered before such a decision is made.
HOW CAN YOU HELP CONTROL THE SPREAD OF FeLV INFECTION?
Catteries and homes with more than one cat run a greater risk of FeLV infection than do homes with one cat. Repeated testing of all cats, isolation of diseased cats, and testing and isolation of any cats added to the home will help control the infection.