Feline leukemia virus (FeLV) infection affects cats in different ways. Some cats can be completely free of any clinical signs if their immune system is able to handle the virus well. Other cats can develop secondary infections with other viruses and bacteria due to immunosuppression. Some cats unfortunately develop cancers such as leukemia and lymphoma or profound anemia as a direct result of FeLV infection.
Cats are most likely to acquire a FeLV infection during their first year of life and/or when they have regular/continual contact with an infected cat. Kittens can get it directly from the mother either in utero or during nursing. Cats can acquire an infection from the bodily fluids of infected cats. Mutual grooming, sharing food/water bowls, sharing litter boxes or fighting are all possible means of transmission.