For the past couple of months, every one of us has focused on measures to prevent themselves from contracting COVID-19. Now that the curve seems to be flattened, we have time to think about other issues. May is Pet Cancer Awareness month. Since lymphoma is the most common tumor of dogs treated by AMC cancer specialists, I chose this cancer as the subject of today’s blogpost.

Treatment for lymphoma requires chemotherapy since lymphoma occurs throughout the body and is not localized to one site, unlike many other tumors. No one wants their favorite fur person to need chemotherapy, so what can we do to prevent lymphoma?

Environmental Factors to Avoid

Environmental exposure to a cancer-causing substance unavoidably increases the risk of cancer. For example, asphalt workers have a higher risk of cancer because they are exposed to coal tar pitch in asphalt. In a British study using data on environmental levels of radon, herbicides and fungicides, researchers determined that lymphoma in dogs was associated with fungicide exposure. Clustering of British dogs with lymphoma near London and in southwest England, lends support to the theory that unidentified environmental factors also play a role in the development of lymphoma. Similar studies from France and Brazil linked lymphoma with exposure to polluted sites, waste incinerators and radioactive waste. However, none of these studies prove environmental exposures cause lymphoma in the dog, they only identify an association between the exposure and lymphoma. Further study is necessary, but keeping your dog away from these environmental factors when possible is a sensible move.

Hormonal Factors

Hormones impact cancer risk in humans. For example, women who’ve never had a child have a greater risk of breast cancer than those who’ve had children. A similar effect could be true for dogs, so veterinary researchers at the University of Missouri studied the effect of hormones on the development of lymphoma using a database of over one million dogs. These researchers compared spayed and neutered dogs to intact dogs, since spaying and neutering stops reproductive hormone production. They found that female dogs have a lower risk of lymphoma than male dogs and that unspayed female dogs have a lower risk than spayed females. However, spaying has health benefits which may be greater than the risk of lymphoma. Dog owners should discuss the risks and benefits of spaying with their veterinarian.

Factors Within Your Control

If your rescue dog was spayed when you got her, or you live in an urban environment, you have no control over hormones or pollutants and their association with lymphoma. What you can control is your dog’s weight. Mounting scientific evidence indicates that dogs with an ideal body weight live longer and healthier than overweight dogs. A recent study concludes that dogs with an ideal bodyweight live as many as 3 years longer than overweight dogs of the same breed. Maybe you can’t prevent lymphoma in your dog, but you can make him live longer by keeping his weight in check. Unsure if your dog is overweight? Check out our blogpost on assessing Body Condition Score (BCS) in dogs with a few famous friends as examples.