Lymphosarcoma (lymphoma) is a malignant cancer originating in lymphocytes, which are found in lymph nodes and almost all the organs and tissues around the body. As with all cancers, lymphoma occurs when some of these cells mutate into malignant cells, then divide uncontrollably into abnormal, cancerous tissue.
Lymphoma is probably the most common type of cancer in cats and not uncommon in dogs. Like most cancers, middle-aged to older animals are most at risk. However lymphoma is unique in that it can be associated with feline leukaemia virus (FeLV) infection in cats. Cats that are infected with FeLV can develop lymphoma as young as three years of age.
As lymphocytes and lymphoid tissues are found all over the body, lymphoma can occur anywhere. In cats, the most common sites are the lymph nodes, gastrointestinal system, inside the chest cavity and the kidneys. In dogs, the lymph nodes, liver and gastrointestinal tract are the most common sites. Humans also get lymphoma and one particular type, Hodgkin’s lymphoma, is fairly well known. This is the form of the disease that Delta Goodram battled successfully a few years ago!
Signs of the disease are often non-specific and usually relate to the system that is affected. If multiple lymph nodes are affected, the lymph nodes may be seen or felt as ‘lumps’ for example behind the jaw, in the groin and in front of the shoulders. If the gastrointestinal tract is affected, the pet may be vomiting or have diarrhoea with or without blood in the faeces. Renal (kidney) lymphoma may manifest as excessive drinking or urination over a period of time and there may be blood in the urine. There may also be non-specific signs such as weight loss and lethargy. Often and especially with cats (the experts in hiding their illnesses), there is a very subtle and gradual decline in appetite and demeanour as well as intermittent vomiting and diarrhoea. This was the case with our very own front desk cat Alex (Alexander the Great), the enormous regal elderly boy that you may have seen in our reception area.
The first step to diagnosing lymphoma is a biopsy. In some cases, a fine needle aspirate may confirm the disease. The vet may then recommend a surgical or ultrasound-guided biopsy for histopathology in order to differentiate between the two types of lymphoma, B-Cell and T-Cell lymphoma.
The silver lining to lymphoma is that itresponds fairly well to chemotherapy compared to other types of cancers, and we have had several patients who have gone into remission or have been cured with this treatment. Chemotherapy can be expensive and can have side effects, however these are often not as bad as in humans and we have a good chance of achieving remission with lymphoma in dogs and cats.
Alex is undergoing chemotherapy for what we suspect is intestinal lymphoma, and he is doing pretty well so far. He is a well loved cat and we hope that he will continue to respond to his treatment.