At what age can kittens be tested for feline leukemia virus (FeLV)?

Testing Kittens for Feline Leukemia Virus (FeLV)

Kittens should be tested for feline leukemia virus (FeLV) at 8-9 weeks of age or older, with cats younger than 1 year of age being most susceptible to infection. 1

Age Considerations for FeLV Testing

• Kittens are especially susceptible to FeLV infection, with younger cats having a significantly higher risk of developing persistent viremia compared to adult cats 1, 2
• Testing should be performed when obtaining a new kitten, particularly before introducing them to other cats in the household 3
• For newly acquired kittens, testing should be done as soon as possible after they are acquired, especially if they have unknown exposure history 3

Testing Recommendations

• When adopting a cat, select one that is at least 1 year of age and in good health to reduce the risk of acquiring a cat with FeLV infection 4
• If adopting a younger kitten, be aware that:
  • Virus may appear in the blood sooner in cats that develop persistent viremia than in transiently viremic cats 5
  • A single negative test in a very young kitten may not be definitive, as the virus may not yet be detectable 3
  • Repeat testing may be necessary to confirm infection status 3

Testing Methods

• Three primary methods are used to detect FeLV infection 5:
  • Virus isolation (can detect infection earliest)
  • Immunofluorescence on blood smears
  • Enzyme-linked immunosorbent assay (ELISA)
• In low-prevalence areas, a positive test result in a healthy cat should be confirmed with a second test, preferably PCR for provirus, to avoid false-positive results 1

Clinical Implications

• FeLV infection can lead to serious health consequences including:
  • Depression of the immune system
  • Anemia
  • Lymphoma
  • Other less common conditions including immune-mediated disease, chronic enteritis, and reproductive disorders 1
• Most cats with persistent FeLV viremia die within 2-3 years of infection 1
• Knowing a cat's FeLV status early allows for appropriate management and prevention of spread to other cats 3

Prevention and Management

• All cats with uncertain FeLV status should be tested prior to vaccination 1
• Vaccination against FeLV is recommended for all healthy kittens at potential risk of exposure 1
• Vaccination schedule should begin at 8-9 weeks of age, with a second vaccination at 12 weeks, followed by a booster 1 year later 1
• FeLV-positive cats should be kept indoors to prevent transmission to other cats 1

Common Pitfalls in FeLV Testing

• Testing only once may miss infections in the early stages 3
• Assuming adult cats are not susceptible to infection (they are, but have lower susceptibility than kittens) 2
• Failing to retest asymptomatic FeLV-positive cats to confirm persistent infection 1
• Not considering that transient viremia can occur, with some cats eliminating the virus after initial infection 5

Remember that early detection of FeLV is crucial for proper management of infected cats and prevention of transmission to other cats in multi-cat households.