Feline Leukemia Virus (FeLV)

Feline Leukemia Virus (FeLV)

By: Dr. Debra Primovic

Section: Overview

Feline leukemia virus (FeLV) is a viral disease of domestic cats that impairs immune system function and causes some types of cancer. FeLV is transmitted by bite wounds, shared dishes or litter pans, or close contact (grooming). Kittens can be born with FeLV or acquire the virus through their mother's milk.

The average age of infection is 3 years and male cats may have a higher prevalence of infection than female cats. The rate of FeLV infection is higher in multi-cat households, catteries and urban areas with high cat populations. The FeLV infection rate ranges from 2 to 13 percent in the general cat population.

FeLV is destroyed in the environment within minutes. There is no evidence of transmission of FeLV from cats to humans. The course of FeLV infection is variable, and there are 3 main stages of infection.



Approximately 33 percent of FeLV-infected cats are infected briefly but are able to eliminate the virus within 4 to 6 weeks. Such transiently infected cats do not become ill or develop FeLV-related disorders.

  • Another 33 percent of FeLV-infected cats develop FeLV-related disease with approximately 60 percent mortality within 2 years.

  • The remaining 33 percent of infected cats cannot completely eliminate the virus, but do not usually develop FeLV-related disease. Such infections cannot be detected with routine blood tests, and require special diagnostic tests such as bone marrow culture of the virus or identification by a special molecular biology technique called polymerase chain reaction (PCR). In a small percentage of these cats, reactivation of the virus is possible. Latent infection also may explain development of certain types of cancers which develop in older cats.

  • FeLV-associated diseases usually are categorized as neoplastic (cancer) or non-neoplastic (include impairment of immune function and development of secondary infections).

    What to Watch For

  • Secondary infections
  • Anemia
  • Difficulty swallowing or eating
  • Weight Loss
  • Difficulty breathing
  • Eye problems
  • Coughing
  • Lethargy
  • Poor wound healing

     
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