Investigating a New Treatment for Hemangiosarcoma

Unfortunately, the cause of lymphoma in dogs is not known. Although several possible causes such as viruses, bacteria, chemical exposure, and physical factors such as strong magnetic fields have been investigated, the cause of this cancer remains obscure. Suppression of the immune system is a known risk factor for the development of lymphoma in humans. Evidence for this includes increased rates of lymphoma in humans infected with the HIV virus or are on immune-suppressing drugs following organ transplantation surgery. However, the link between immune suppression and lymphoma in dogs is not clearly established.

The best way to diagnose lymphoma is to perform a biopsy. A biopsy is a minor surgical procedure to remove a piece of lymph node or other organ affected by cancer. The most common methods for lymph node biopsy are Tru-cut needle biopsy, incisional wedge biopsy, or removal of an entire lymph node (excisional biopsy). The larger the biopsy sample, the better the chance for an accurate diagnosis of lymphoma. In addition to biopsy, several staging tests are also performed for dogs with lymphoma. The purpose of the staging tests is to determine how far the lymphoma has spread throughout your dog’s body. In general, the more places the lymphoma has spread to, the poorer the dog’s prognosis. However, dogs with very advanced lymphoma can still be treated and experience cancer remission (see more on treatment below). Staging tests also help us assess whether your dog has any other conditions that may affect treatment decisions or overall prognosis. The staging tests we typically recommend include blood tests, a  urinalysis, x-rays of the chest and abdomen, an abdominal sonogram, and a bone marrow aspirate. Organs that appear abnormal on sonogram can be sampled with a small needle (fine needle aspirate) to confirm the presence of lymphoma.

No preventative measures are currently available but it is recommended that breeds at a higher risk of developing lymphoma being screened by their veterinarian on a regular basis in an attempt to identify the disease at the earliest stage possible.

The most effective therapy for most types of canine lymphoma is chemotherapy. In some cases, surgery or radiation therapy may also be recommended. There are numerous chemotherapy treatment protocols for dogs with multicentric lymphoma. As discussed below, most dogs with lymphoma experience remission of their cancer following treatment, and side effects are usually not severe. Currently, the protocols that achieve the highest rates of remission and longest overall survival times involve combinations of drugs given over several weeks to months. The median length of survival of dogs with multicentric lymphoma treated with UW-25 chemotherapy is between 9-13 months. (The term “median” implies that 50% of dogs will survive beyond this time point and 50% of treated dogs will die before this time point.) Various other factors, such the type of lymphoma your dog has or its stage of disease, may affect your dog’s overall prognosis.