How Serious is Feline Leukemia (part.2)

What happens to a cat after being exposed to FeLV?

If the cat becomes infected from exposure to FeLV, 2-4 weeks later, in the acute stage of infection, large numbers of the virus can be found in the bloodstream (viremia). Cats in the acute phase may not show signs of disease. If they do, the signs are usually fever, lethargy, diarrhea and swollen lymph nodes (lymphadenopathy). When a cat is exposed to FeLV, several things can happen:

• Some cats will not be infected due to inadequate exposure and a good immune response.
• Some cats will develop a latent infection; these cats will not be able to destroy all of the viral RNA and DNA, but will be able to hold it in check. This is called a latent or regressive infection. These cats show no signs of infection and usually do not shed virus in their saliva or other body secretions.
• Some cats will become persistently infected; these cats will not develop an adequate immune response and will remain permanently infected with FeLV. This is called a progressive infection. These cats will shed large amounts of virus in their saliva and often develop FeLV-associated diseases within a few years.

Age is a very important factor in determining what will happen after a cat is exposed to FeLV. Almost all FeLV-exposed kittens less than 8 weeks of age will have persistent viremia, show signs of disease during the acute phase, and become permanently infected.

What diseases are associated with FeLV infection?
FeLV can cause:

• Weight loss
• Fever
• Immunodeficiency and infections
• Anemia
• Immune-mediated diseases
• Reproductive problems
• Gastrointestinal disease
• Neurologic disease
• Platelet disorders
• Lymphadenopathy (enlarged lymph nodes)
• Cancer
• Respiratory and eye problems
• Oral disease

Immunodeficiency

FeLV can decrease the effectiveness of the immune system and result in increased susceptibility to bacterial, fungal, protozoan, and other viral infections. Feline Infectious Peritonitis (FIP), for instance, is much more common in FeLV-infected cats. The first indication of FeLV infection in some cats is recurrent bacterial infections of the mouth. Recurrent skin or respiratory infections can also occur.

Anemia

FeLV often affects cells in the bone marrow. As a result, most FeLV-infected cats have a nonregenerative anemia.

Immune-mediated Diseases

Large amounts of the FeLV antigens combine with the cat's antibodies and form complexes which can be deposited in the kidneys, blood vessels, or joints.

Reproductive Problems

FeLV infection is often associated with infertility in cats. Abortions, stillbirths, and fetal resorption are also more common in FeLV-infected queens. "Fading kitten syndrome" may result from FeLV infection of the fetuses or newborn kittens.

Gastrointestinal Disease

FeLV-caused cancers of the stomach or intestines. FeLV-associated changes in the intestinal wall can cause anorexia, vomiting, diarrhea, and weight loss. Parasites and bacteria more commonly multiply and cause diarrhea in FeLV-infected cats.

Neurologic Disease

Seizures, blindness, paralysis, changes in behavior, and ataxia (loss of balance) can be seen in FeLV-infected cats. These symptoms may be caused directly by FeLV or by parasites (Toxoplasma gondii) and fungi (Cryptococcosis), which occur more often in immunosuppressed animals.
Platelet Disorders: A decrease in the number of platelets, (thrombocytopenia), or a dysfunction of platelets sometimes occurs in cats infected with FeLV.

Lymphadenopathy

Lymph nodes in the abdomen and other parts of the body are often enlarged.

Cancer

Approximately 30% of FeLV-infected cats will develop cancer. Usually, the cancer is in the form of tumors of lymphocytes or red blood cells, and includes lymphosarcoma, lymphoid leukemia, myeloid leukemia, and erythremic myelosis. Not all cats infected with FeLV will develop leukemia or lymphosarcoma, and not all cases of leukemia and lymphosarcoma are caused by FeLV.

Respiratory and eye problems

Cats may show signs of upper respiratory disease, especially nasal discharge (runny nose). Eye discharge may also be seen.

Oral disease

Ulcers in the mouth and infections of the mouth (stomatitis) and gums (gingivitis) are common.