Lymphoma In Cocker Spaniels

Lymphomas, are a type of cancer that originates in a subset of white blood cells called 'lymphocytes'. Lymphocytes are an important part of the immune system. The main difference between Hodgkin and non-Hodgkin lymphoma is in the specific lymphocyte each involves.

White blood cells (WBCs), or leukocytes, are cells of the immune system involved in defending the body against both infectious disease & foreign materials. Leukocytes are produced & derived from the bone marrow from cells known as a hematopoietic stem cell. Leukocytes are found throughout the body, including the blood and lymphatic system.

Signs & Symptoms

Symptoms can vary and this relates to the stage of the disease, amount of tumour and the location of the lymphoma but may include:

• Generalized lymph node enlargement (swollen glands)
• Lethargy
• Weight loss & loss of appetite
• Increased drinking/urination
• Vomiting and/or diarrhoea
• Difficulty breathing

Diagnosis

A thorough and full physical examination including, complete blood count, platelet count, biochemical profile, urinalysis & fine needle aspirate or excisional biopsy of the lymph node. Other tests may include chest and abdominal radiographs, abdominal ultrasound and ultrasound guided aspirates of the liver and spleen for cytologic evaluation, and bone marrow aspirate. An assessment should be made to check for hypercalcemia, kidney function and to check whether the platelet and neutrophil count is normal.

Once a diagnosis of lymphoma has been established, it is necessary that the cancer is 'staged'. Staging is the term to describe the methods used to determine the extent of the lymphoma i.e. how far it has spread throughout the dogs body. The degree of spread usually affects the way in which a dog is treated.

Treatment

Chemotherapy is the desired treatment. The exact treatment regime (single drug/multi-drug/type of drug or drugs) will vary depending on the vet and on the costs involved and the owner's financial situation i.e. self paying or insurance claim.

Treatment for lymphoma in the dog is considered one of the more successful cancer treatments & can often be performed by an owners own vet without the need or increased expense of taking the dog to a specialist centre or vet school.

Prognosis

The decision whether to go down the chemotherapy route is governed by the wishes of an owner and the financial implications involved. It is likely that untreated dogs will have a life expectancy of around 4 - 6 weeks following diagnosis. Some owners may decide that they do not wish to put their pet through the process of chemotherapy for either fear of making the dog uncomfortable or due to the dog's age or unfortunately the cost is prohibitive.

If chemotherapy is attempted using one of the recommended protocols, life expectancy can be extended. Approximately 75% of dogs treated with chemotherapy will go into remission. The length of remission varies but can be averaged out at around 6 - 11 months before further chemotherapy is needed. Second time around the remission rate is not quite so high. It is estimated that approximately 40-45% of dogs with lymphoma live one year with treatment. Less than 20% of dogs with lymphoma live 2 years with treatment. At some point the tumour becomes resistant to therapy and no further remissions can be obtained. Although these do not sound long periods of time, given the expected normal life expectancy of a dog, the time bought through chemotherapy can be worth the effort & expense particularly as dogs appear to tolerate chemotherapy well (far better than humans!).  Once remission is achieved, dogs are generally fit and well and back to good health.

Unfortunately, lymphoma is a life limiting disease and despite chemotherapy there comes a time where remission is not achievable and sadly the cancer will return & infiltrate an organ to such an extent that organ fails (often this is the bone marrow or the liver). This is the time to say goodbye to prevent suffering as unfortunately death is inevitable. Signs that the sad decision has to be made are the dog being reluctant to eat, vomiting/diarrhoea, weakness/lethargy/depression.