Animals with the blood form of lymphoma, called leukemia, tend to be very sick. Dogs and cats with lymphoma of the brain or spinal cord may be paralyzed, have seizures or be demented. The skin form of lymphoma occurs in dogs but is rare in cats. There may be one skin lump or many. The skin lesions are often raw and ulcerated.
Cats can develop a form of lymphoma in the nose.
In many cases a diagnosis of lymphoma can be made by taking a small needle sample from the tumor. The method used to make a diagnosis of lymphoma varies with the form. The generalized form is often easy to diagnose by obtaining a small needle sample from one of the lymph nodes for microscopic evaluation although in a few cases a surgical biopsy may be needed. Ultrasound is a good method to look inside organs. The texture of the liver and spleen is often abnormal when they contain cancer cells.