Lymphoma in dogs

Lymphoma in dogs

Lymphoma is one of the most common malignant tumors to occur in dogs. The cause is genetic, but there also suspected environmental factors involved, including in one study an increased risk with the use of the herbicide 2,4-D. This risk was not confirmed in another study.
Commonly affected breeds
· Boxer
· Scottish Terrier
· Basset Hound
· Airedale Terrier
· Chow Chow
· German Shepherd Dog
· Poodle
· St. Bernard
· Bulldog
· Beagle
· Rottweiler
· The Golden Retriever is especially susceptible to developing lymphoma, with a lifetime risk of 1:8.

Classification

The cancer is classified into low and high grade types. Classification is also based on location. The four location types are multicentric, mediastinal, gastrointestinal, and extranodal (involving the kidney, central nervous system, skin, heart, or eye). Multicentric lymphoma, the most common type (by greater than 80 percent), is found in the lymph nodes, with or without involvement in the liver, spleen, or bone marrow. Mediastinal lymphoma occurs in the lymph nodes in that area and possibly the thymus.

Gastrointestinal lymphoma occurs as either a solitary tumor or diffuse invasion of the stomach or intestines, with or without involvement in the surrounding lymph nodes, liver or spleen. Classification is further based on involvement of B-lymphocytes or T-lymphocytes. Approximately 70 percent are B-cell lymphoma. Cutaneous lymphoma can be classified as epitheliotropic (closely conforming to the epidermis) or non-epitheliotropic. The epitheliotropic form is typically of T-cell origin and is also called mycosis fungoides. The non-epitheliotropic form is typically of B-cell origin.