Great strides have been made in the control and prevention of feline leukemia virus and feline immunodeficiency virus. FeLV can be passed from a mother cat to her kittens either through the placenta or through her milk. It is passed by cats licking, grooming and fighting with each other. FeLV can be dormant in a cat's body for weeks to years and then be activated and cause severe disease and death. Signs that may indicate FeLV include weight loss, anemia, lethargy, dehydration, jaundice, susceptibility to other infections and lymph node cancer. Reliable methods for screening and vaccination are available.

FIV is not passed from a queen to her kittens. The most common mode of transmission of FIV is through cats biting and fighting with each other. There is no vaccine to prevent against FIV. Cats with FIV can live relatively normal lives. Signs include gingivitis, slow healing wounds, bacterial infections that take longer to respond to antibiotics, weight loss, blood cell abnormalities, lymph node enlargement and various secondary infections. Reliable screening tests are available for this virus, although there is no cure.