Posted November 22, 2016 in Cat Health
What is feline leukemia? Feline leukemia is a cancerous disease caused by feline leukemia virus (FeLV). FeLV causes diseases other than leukemia including immunodeficiency and additional cancers. Cats may not start to show signs of disease for months or years after being infected with FeLV. Infection with FeLV is a major cause of illness and death in domestic cats.
What are the characteristics of feline leukemia virus?
FeLV is a type of virus called a retrovirus. Other notable feline diseases in the same family are feline immunodeficiency virus (FIV) and human immunodeficiency virus (HIV the virus that causes AIDS).
Retroviruses are species-specific. This means a feline retrovirus will only infect cats; a human retrovirus will only infect humans. Retroviruses are made up of RNA. In the host the RNA is transcribed into DNA and incorporated into the DNA of the host’s cells.
Retroviruses are fragile being easily inactivated by ultraviolet light, heat, detergents, and drying. Retroviruses are widespread in nature. As a matter of fact they have been around for so many millions of years parts of a feline retrovirus are actually incorporated into every cat’s DNA. This is called “endogenous” FeLV DNA. This is passed from generation to generation.
There are three subgroups of FeLV and each tends to cause a different type of disease:
How common is FeLV infection?
It is estimated that 2-3% of healthy cats are infected with FeLV. Approximately 20-30% of the healthy cats living in infected multi-cat households and catteries are infected.
How is FeLV transmitted?
Large amounts of FeLV are excreted in the saliva. Therefore the most common mode of transmission is through nose-to-nose contact, mutual grooming, and shared food and water bowls. Bites are a very efficient way to transmit FeLV.
FeLV can also be found in lesser amounts in tears, urine, and feces. Thus litter boxes could be a source of infection in multi-cat households or catteries. FeLV can also be transmitted across the placenta (in utero) and through the milk.
It takes large amounts of virus to infect an adult cat so usually prolonged contact is necessary for transmission.
What happens to a cat after being exposed to FeLV?
If the cat becomes infected from the exposure 2-4 weeks later in the acute stage of infection large numbers of the virus can be found in the bloodstream. Cats in the acute phase usually do not show signs of disease. If they do show signs of disease, they are usually mild fever, slight lethargy, and swollen lymph nodes. When an adult cat is exposed to FeLV four things can happen:
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 and show signs of disease during the acute phase. As kittens get older there is the probability of becoming persistently infected after exposure lessens until it reaches approximately 30% in adulthood.
The prevalence of FeLV infection is highest in cats between 1 and 6 years of age with a mean age of 3 years. Male cats are twice as likely to be infected. This may be due to the frequency in which intact males roam and fight.
What diseases are caused by FeLV?
FeLV can cause:
What are the clinical signs of disease?
The clinical signs of disease are going to be variable because so many body systems can be affected. Loss of appetite, fever, weight loss, and weakness are the first clinical signs of disease commonly seen in infected cats.
How is FeLV infection diagnosed?
Blood tests are commonly used to test both asymptomatic and symptomatic cats for FeLV antigen. The ELISA test can be performed in a veterinarian’s office. The ELISA test can be performed on blood serum saliva or tears. Using serum will reduce the possibility of obtaining a false positive test (a positive test in an uninfected animal).
Can FeLV be prevented?
Because of the advances in medical science and veterinary care there are several vaccinations available today that protect your cat against FeLV. A few of these vaccines include Fel-O-Guard Plus and Fel-O-Vax. Remember an ounce of prevention is worth a pound of cure. Guard your cat against the danger of feline leukemia.