Cats infected with feline leukemia virus may exhibit symptoms such as pale gums, enlarged lymph nodes, a yellow color in the mouth and whites of eyes, weight loss or appetite loss, states WebMD. Other indications are poor coat condition, fever, diarrhea, respiratory problems, bladder or skin infections, and progressive weakness.
If a cat has symptoms of the feline leukemia virus, known as FeLV, then a blood test called an ELISA can diagnose the disease, explains WebMD. This blood test identifies the leukemia proteins, and veterinarians can track the progress of the disease with routine veterinarian visits. There is presently no cure for the feline leukemia virus, but regular veterinarian visits can prevent further infection and manage the various stages of the disease.