Lymphoma

A common blood cancer that occurs in dogs

Overview

Lymphoma is one of the most common blood cancers diagnosed in dogs. There are two types of lymphoma - T cell and B cell tumors. B cell tumors are the most common and tend to respond better to treatment than T cell tumors.

Breeds commonly affected:

• Boxer
• German Shepherd
• Poodle
• Scottish Terrier
• Golden Retriever

Signs

The most common clinical sign is the development of multiple enlarged lymph nodes. Dogs can appear the same or unwell. It is a rapidly progressive disease and without treatment, unfortunately, a dog can die within a month of diagnosis. 

Commonly affected sites:

• Lymph nodes
• Liver 
• Spleen
• Mucocutaneous
• Central nervous system
• Bone

Lymph node staging

Stage I	single enlarged lymph node
Stage II	multiple enlarged nodes on either the front half or back half of the body
Stage III	multiple enlarged nodes on both front and back of the body
Stage IV	liver and/or spleen involvement
Stage V	bone marrow or other organs (gastrointestinal, skin, nervous) involvement

Management

As lymphoma is caused by a white blood cell disorder, it can occur anywhere in the body and treatment cannot be treated surgically.

Treatment options include:

• Prednisone
• Chemotherapy
• A combination of cyclophosphamide, doxirubicin, vincristine, prednisone (CHOP)
• A combination of vincristine, cyclophosphamide, prednisone, doxorubicin, and L-asparaginase (VELCAP protocol)
• Monoclonal antibody therapy
• +/- bone marrow transplantation
• +/- radiation therapy
• Lymphoma vaccine

Chemotherapy may involve the use of multiple chemotherapy drugs over a period of months.

Chemotherapy and radiation therapy are the treatments of choice for dogs with B-cell lymphoma. Fortunately, 80-90% of dogs with B-cell lymphoma will respond successfully to chemotherapy. The dog is then confirmed, "in remission", with remission in 84% of dogs lasting around 9 months. Unfortunately, most dogs will experience a relapse in the future.

T-cell lymphoma tends to be less responsive to therapy with shorter survival times.

Prognosis

Dogs that are sick or have a T-cell lymphoma have a lower chance of remission and if they reach remission, it is shorter than the remission of a healthy dog with B-cell lymphoma. 

The mean survival time for dogs treated with prednisone alone is around 2 months.

The results for chemotherapy are highly variable with a mean survival time averaging 1 year.

CHOP and VELCAP protocols have a mean survival time of around 1 year. 

Studies suggest that about 10-25% of dogs will live for 2 years or longer.

References

Zemann B, Moore AS, et al. A combination chemotherapy protocol (VELCAP-L) for dogs with lymphoma. J Vet Internal Med 12 465-470, 1998.

Moore AS, Cotter SM et al. Evaluation of a discontinuous treatment protocol (VELCAP-S) for canine lymphoma. J Vet Internal Med 15 348-354, 2001

Moore AS, London CA, et al. Lomustine (CCNU) for the treatment of relapsed lymphoma in dogs. J Vet Internal Med 13 395-398, 1999.

Morrison-Collister KE, Rassnick KM, Northrup NC, Kristal O, Chretin JD, Williams LE, Cotter SM, Moore AS. A combination chemotherapy protocol with MOPP and CCNU consolidation (Tufts VELCAP-SC) for the treatment of canine lymphoma. Veterinary and Comparative Oncology 1, 180-190, 2004

Rassnick KM, Mauldin GE, Al-Sarraf R, Mauldin GN, Moore AS, and Mooney SC. MOPP chemotherapy for treatment of resistant lymphoma in dogs: a retrospective study of 117 cases (1989-2000) J Vet Internal Med 16, 576-580, 2002.