Lymphoma is one of the most common forms of cancer in dogs. Every time I diagnose one of my patients with lymphoma I have what boils down to a "bad news : a little bit of good news" discussion with my client.
First the bad news: Lymphoma in dogs is almost always a fatal disease. But the good news is that unlike some other types of canine cancer, we can sometimes manage it quite successfully for an extended period of time.
For the minimalists amongst us, prednisone alone can make a dog feel almost back to normal for several weeks to months. More aggressive chemotherapy protocols can help many dogs live happily for an additional year or even longer. While this might not sound like much, when you put it into the perspective of a dog’s short life, it is significant.
A new, experimental vaccine might make the "good news" associated with canine lymphoma even better.
Researchers at the University of Pennsylvania recently tested a vaccine that is made by growing B-cells (a type of lymphocyte, the cells that become cancerous in lymphoma) from the patient’s own blood. These cells were then loaded with RNA that had been isolated from the dog’s tumor and injected back into the patient. Dogs in the study received three vaccinations after standard chemotherapy protocols achieved remission, and the progression of their disease was compared to a group of dogs that received chemotherapy only.
Dogs that were vaccinated and those in the control group both had similar rates of relapse. However, when treated with a second round of chemotherapy called a rescue protocol, dogs that were vaccinated had much better survival rates than those in the control group. Some vaccinated dogs were still disease-free after three years.
According to Nicola Mason, assistant professor of medicine at the University of Pennsylvania School of Veterinary Medicine and one of the authors of the study:
Though vaccinated and unvaccinated dogs relapsed with clinical disease at the same time, 40 percent of vaccinated dogs that relapsed experienced long-term survival after a second round of chemotherapy; only 7 percent of unvaccinated dogs that relapsed and were treated with the same rescue chemotherapy protocol survived long term. Furthermore, when the vaccinated long-term survivors did eventually die, they showed no evidence of lymphoma on full necropsy.
It appears that chemotherapy and the vaccine work together to improve survivability. The details of how this might work are still unclear, but continued research could lead to even more exciting results. As Dr. Mason said:
These dogs just received three doses of vaccine, three weeks apart. If we kept boosting the immune system in this way by vaccination, perhaps the dogs would not relapse in the first place.
The dogs in this study had what is called non-Hodgkin’s lymphoma in the human medical world. Fingers crossed that this research will lead to great advances in treatment for both people and pets with this all-too-common disease.
Dr. Jennifer Coates