Canine malignant lymphoma is a cancer that typically affects dogs. It is a result of continual growth of destructive lymphoid cells that ultimately cause death. Lymphoma usually springs up from organized lymphoid tissues in the bone marrow, thymus, lymph nodes, and spleen. There are other usual sites like the skin, eye, central nervous system, testis, and bone. The disease is quite common, though its source and causes are not understood properly. There are some factors that can probably cause the disease, such as viral infection, ecological pollution with herbicides, exposure to a magnetic field, genetic abnormalities, and immune system dysfunction.
The signs of canine lymphoma tend to contrast depending on the body part affected and how extensive the disease is. Dogs usually exhibit four distinctive forms of lymphoma:
- 1) Multi-centric lymphoma, which grows in multiple places in the body.
- 2) Alimentary lymphoma, which develops in the digestive system.
- 3) Mediastinal lymphoma, which develops within the chest.
- 4) Extra-nodal lymphoma, which may affect the kidneys, central nervous system, or skin.
Multi-centric lymphoma is indeed the most widespread form of lymphoma, responsible for around 80% of cases. One of the initial signs of multi-centric lymphoma is the fast and painless swelling of lymph nodes, which can expand 3 to 10 times their regular size. Additionally, it is also possible for the cancerous lymphocytes to migrate into internal organs like the spleen, liver, and bone marrow. As the tumours grow and multiply, and the disease progresses to its later stages, affected dogs may display signs of illness. These may include loss of energy, weakness, fever, poor appetite, and gloominess.
Alimentary lymphoma is not as widespread, affecting less than 10% of all cases of canine lymphoma. Dogs suffering from this form of lymphoma may develop signs associated with upset stomachs, like vomiting and abdominal pain. When the disease attacks a big portion of the intestinal tract, it causes problems with proper digestion of food. This means that dogs may experience a lack of appetite, vomiting, diarrhea, and persistent weight loss.
Mediastinal lymphoma is a rare form of the disease, with affected dogs having inflamed thymus and lymph nodes. As the disease progresses, there may be signs like breathing problems due to fluid build-up in the chest and lungs. The tumour may also obstruct the vein that carries blood from the upper body into the heart. Apart from breathing complications, some dogs may drink abnormal quantities of water and consequently pass large amounts of urine. This can be due to a rise in calcium levels in the blood, a disorder affecting 10% to 40% of dogs with lymphoma.
The medical issues linked to extra-nodal lymphoma differ, depending on the affected organ. Skin lymphoma shows particular symptoms like sores that are raised and slow-to-heal, or pervasive flaking areas. Symptoms of lymphoma include respiratory problems (lungs), kidney failure, loss of sight, and seizures (central nervous system).
Diagnosis of canine lymphoma is easily done by testing the affected organ system. Dogs with multi-centric lymphoma can undergo a needle biopsy of their inflamed lymph nodes, as this will provide sufficient cells to verify the diagnosis.
Treatment And Prognosis of Canine malignant lymphoma
Successful treatment of multi-centric canine lymphoma involves chemotherapy and a combination of drugs, resulting in more than a 90% improvement rate for all dogs. Treatment of individual dogs is dependent on the drugs administered, dosage, and regularity and length of treatment. A dog with B-cell lymphoma and undergoing chemotherapy treatment has an expected survival period of about 9 to 12 months. Dogs with T-cell lymphoma generally have shorter survival times i.e. about 6 months. Dogs that are resistant to the normal drugs may recover when alternative treatment plans are used, such as other drugs or radiation.
There is greater complexity when it comes to dealing with the other forms of lymphoma. Alimentary lymphoma that is localized in one area can be successfully treated using combination therapy, and surgery to eradicate the tumour. However, if the lymphoma has extended all over the intestinal tract, there tends to be little effective response to treatment, with survival periods shortening to less than 3 months. Dogs with mediastinal lymphoma generally show substantial progress in survival times and quality-of-life scores, especially when combination chemotherapy is used, with or without radiation therapy. In T-cell lymphoma cases, remission averages about 6 months. Dogs with an unusually elevated level of calcium in the blood, a situation regularly linked to mediastinal lymphoma, are also unlikely to experience prolonged survival times. Extra-nodal lymphoma, such as the one affecting the skin, can be controlled using appropriate surgery, radiation, and chemotherapy. However, the disease rarely responds to medical treatment.