Lymphoma in Dogs

Lymphoma or lymphosarcoma is one of the most prevalent forms of cancer that affects the lymphatic system, which is an indispensable part of the immune system. The disease is caused by the multiplication of the malignant lymphocytes in lymph nodes. It can also affect the lymphoid tissues of the liver, bone marrow, skin and gastrointestinal tract. The disease is commonly found in middle-aged and old dogs. The breeds of dogs, which are more vulnerable to lymphoma include Scottish terriers, Golden retrievers, Boxers, Basset hounds, German shepherds, Beagles, Bulldogs and Rottweilers.

Lymphoma in Canines

Classification

The disease is classified into several types, on the basis of the location of the cancerous tumors. The multicentric tumor is the most common type of lymphoma and is usually found in lymph nodes. On the other hand, the gastrointestinal lymphoma originates in the stomach, intestine, liver and lymph nodes. Mediastinal is another form of lymphoma, that affects the lymph nodes of the thorax and thymus. The cutaneous form of lymphoma develops in the skin, while the extranodal form of lymphosarcoma affects the nervous system, heart, eyes and the kidneys. Lymphoblastic leukemia occurs when the disease develops in the bone marrow.

Causes

The exact causes of the development of lymphoma are not known till now, though genetics is believed to play a significant role. Besides, environmental factors like exposure to certain chemicals or substances such as pesticides, herbicides and strong magnetic fields are believed to increase the risk of developing this disease.

Symptoms

The most common symptom is the enlarged lymph nodes that can be identified as a lump under the jaw, armpits, groin or behind the knees. Besides this, the gastrointestinal form can produce symptoms like vomiting, weight loss, loss of appetite, diarrhea, etc. Shortness of breath, heart sounds, accumulation of fluid around the lungs, cough and hypercalcemia (high level of calcium in blood) are associated with the mediastinal form of lymphoma. The cutaneous form of lymphoma can cause lumps in the skin and mouth, while seizures and paralysis can occur if the central nervous system is affected. In addition to this, the disease can cause anemia and a low count of white blood cells, if the bone marrow is affected.

Diagnosis and Treatment

It can be confirmed with the help of a biopsy of the lymph nodes or the affected organs of the body. Other than this, bone marrow or liver and spleen aspiration are also carried out, to gather more information about the disease. X-ray, ultrasound, blood analysis and bone marrow biopsy are performed to detect the location of the cancer.

The diagnosis is also aimed at detecting the stages of the disease, which is generally classified into five stages. If only one lymph or lymphoid tissue in one organ is affected, then it is categorized as stage I, while if the lymph nodes of only one area are affected, then it is defined as stage II. The stage III is characterized by the involvement of all the peripheral lymph nodes, while the stage IV is identified by the involvement of liver and spleen in addition to any of the first three stages. In the stage V, blood or bone marrow is affected in addition to any of the above mentioned four stages.

Treatment usually aims at alleviating the symptoms and prolonging the life of the afflicted dogs, as a complete cure is not possible. The usual treatment of this cancer is chemotherapy. The medications that are used commonly in its treatment are cyclophosphamide, vincristine, prednisone, L-asparaginase, and doxorubicin. Besides, nutrients like arginine, vitamin A, D and B12 are also given to relieve the symptoms of the disease.

Though lymphoma is not permanently curable, early detection and proper treatment can prolong the life of the diseased dogs. If the disease is left untreated, it can lead to death within 2 months. Sometimes, with the help of treatments like chemotherapy, a long remission period can be achieved that can substantially extend the lifespan of the dogs afflicted with lymphoma.