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Cat FeLV (Feline Leukemia Virus)

First discovered in the 1960s, feline leukemia virus is a transmittable RNA retrovirus that can severely inhibit a cat's immune system. It is one of the most commonly diagnosed causes of disease and death in domestic cats.

Because the virus doesn't always manifest symptoms right away, any new cat entering a household-and any sick cat-should be tested for FeLV.

How Do Cats Get FeLV?

The FeLV virus is shed in many bodily fluids, including saliva, nasal secretions, urine, feces and blood. FeLV is most commonly transmitted through direct contact, mutual grooming and through sharing litter boxes, food and water bowls. It can also be passed in utero or through mother's milk. Outdoor cats who get into fights with other cats can transmit the disease through bites and scratches.

What Are the Signs of FeLV?

  • Cats can be infected and show no signs.
  • Loss of appetite and weight loss
  • Pale or inflamed gums
  • Poor coat condition
  • Abcesses
  • Fever
  • Upper respiratory infections
  • Diarrhea and vomiting
  • Seizures
  • Changes in behavior
  • Vision or other eye problems
  • Enlarged lymph nodes
  • Reproductive problems (in females)
  • Jaundice
  • Chronic skin disease
  • Respiratory distress
  • Lethargy

How Is FeLV Diagnosed?

There are several types of tests available to diagnose FeLV. Most veterinarians and shelter professionals use the ELISA (enzyme-linked immunosorbent assay) test, which detects antigen to the FELV virus in the bloodstream. Other tests like the IFA (indirect fluorescent antibody) test or PCR (polymerase chain reaction) test are recommended to confirm positive ELISA test results.

What Happens to Cats Who Are Infected with FeLV?

FeLV weakens an animal's immune system and predisposes cats to a variety of infections and diseases, including anemia, kidney disease and lymphosarcoma, a highly malignant and fatal cancer of the lymph system.