How dogs are helping advance lymphoma research

Pet owners know the worry that sets in when a beloved companion isn’t acting like themself. As in humans, often times an animal's physical symptoms are temporary and resolve on their own. Unfortunately, this is not always the case. Pets can develop serious illness like cancer, too. In dogs, lymphoma is one of the most commonly diagnosed cancers (about 10% of all canine cancers). 

In dogs, lymphoma most often appears as swollen lymph nodes. These may be felt around the neck, chest, or behind the knees. Other symptoms include weight loss and lack of energy. The lymphoma diagnostic process in a dog is very similar to what a human would experience: a physical exam, blood tests, biopsy, imaging. Should lymphoma be confirmed, chemotherapy is a likely treatment path. The CHOP-R protocol (also used in humans) has been demonstrated to be effective in dogs. In fact, studies have shown that that dogs actually tolerate chemotherapy much better than humans. Sometimes surgery and/or radiation are recommended, depending on the location of the lymphoma.

Just like there is clinical research around how to improve treatments for lymphoma and other cancers in humans, there is such activity for dogs, too. For lymphoma specifically, the canine version of the illness is quite similar to the human version. In both dogs and humans, the most common form of lymphoma is Diffuse Large B-Cell Lymphoma. Under a microscope these cancerous cells share many of the same features. And because dogs develop lymphoma spontaneously, just like humans, they are a more realistic model for studying disease behavior. So research to help improve treatments for dogs diagnosed with lymphoma also may help develop better treatments for people, too. This type of partnership between veterinarians and oncologists is called “comparative oncology.”

In one canine study at the University of Missouri, researchers used CAR T-cell therapy in dogs with advanced lymphoma. Genetically engineered immune cells were injected directly into the dogs’ lymph nodes. The results were quite promising: tumors shrank dramatically within days, and many of the dogs experienced a period of remission. Another recent study looked at the cells of almost 300 dogs with lymphoma in order to document genetic findings and correlate mutations to outcomes for optimal treatment planning.

Veterinarians are particularly eager to see new immunotherapy treatments for dogs, but there are obstacles. For example, antibody treatments that show good response in humans cannot be used in dogs because of immune system differences. Yet efforts continue to try and develop a canine antibody. If successful, this could lead to new comparative oncology trials that combine immune-boosting drugs with other immunotherapies, chemotherapy, or targeted therapies. 

As one veterinarian Lauren Trepanier, professor and assistant dean for Clinical and Translational Research at the University of Wisconsin-Madison School of Veterinary Medicine, explained, “Dogs have normal immune systems, and they’re exposed to the same environment that people are. The dog is a very effective sentinel of cancers that occur in both dogs and people.”