Feline lymphoma is one of the most common cat diseases. In fact, cats actually have more cases of lymphoma than humans. Feline lymphoma is most common in cats infected with the feline leukemia virus (FeLV). Age, sex, or breed does not seem to have any bearing on which cats will become infected with the disease. Most cats are diagnosed with feline lymphoma at around age nine or 10. Cats with feline lymphoma develop tumors that can be found just about anywhere in the body. However, there are three areas that are more common to the disease: The lymph nodes The chest cavity (mediastinal lymphoma) The digestive tract and its lymph nodes (alimentary lymphoma) Symptoms vary based on where the tumors exist. The most obvious signs are the following: Mediastinal -- fluid in the lungs and trouble breathing Alimentary -- vomiting, diarrhea, weight loss, and rough coat Lymph node variety -- most common is swelling of the lymph nodes If you see any of these symptoms you should take your cat to the vet right away. Treatment for feline lymphoma usually consists of chemotherapy, and it has a very good prognosis in many cases. Depending on where the lymphoma is located in your cat's body and what type it is, treatment often results in high remission rates and a significant addition to the life span of the cat.