Glossary
Lymphoma
A cancer of the lymphocytes, a type of white blood cell, that most often appears as firm, painless swelling of lymph nodes.
Also called: lymphosarcoma, canine lymphoma, lymph node cancer, swollen glands
Lymphoma is one of the most common cancers in dogs. It arises from lymphocytes, immune cells found throughout the body, so it often first appears as enlarged lymph nodes under the jaw, in front of the shoulders or behind the knees. Affected dogs may otherwise feel well at first, and later lose weight and appetite and become tired.
It usually affects middle-aged and older dogs, and breeds such as the Golden Retriever and the Boxer appear more often. Lymphoma has several forms, and it can also involve the gut, skin or chest.
Any new or growing lump deserves a veterinary exam. A vet confirms lymphoma with a needle sample or biopsy and blood tests, which also show its type. Care options are planned with a veterinarian or veterinary oncologist.
Last reviewed November 8, 2026