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July 1, 2020 – Could certain dogs be more at risk for developing environmentally associated cancers? Dr. Lauren Trepanier, a Morris Animal Foundation-funded cancer researcher, thinks this may be the case.

She’s had boxers all her life and the three she’s owned as an adult all have developed different forms of lymphoma, a cancer of the lymph nodes and lymphatic system. After her last dog, Tucker, developed the disease in his brain, she was fed up and started asking questions.

“It was heartbreaking for me. I’ve also diagnosed lymphoma in other people’s pet dogs more times than I care to remember. I want to decrease the risk of owners having to go through that,” said Dr. Trepanier, the Assistant Dean for Clinical and Translational Research at the University of Wisconsin-Madison.

Although lymphoma is a common tumor, its cause is unknown. In humans, it appears to be associated with chemicals in the environment. That’s one of the reasons she applied for a grant from Morris Animal Foundation to look at how exposures to common environmental chemicals, and individual genetic differences in response to those exposures, puts dogs at risk for common cancers.

When humans are exposed to toxic chemicals in the environment, glutathioneS-transferase (GST) enzymes help neutralize those chemicals. Due to genetic variations in GST enzymes, people vary in their capacity to deactivate environmental hazards. That’s why two people exposed to the same chemical or chemical mixes can have different risk levels for developing cancer.

“We want to know if the same thing is true for dogs and how they react differently on a genetic level,” said Dr. Trepanier. “If we can better understand what sort of chronic household exposures are important in dogs, then we can do a better job of counteracting them and maybe decreasing the incidence of certain cancers.”

For their study, the team is replicating four major forms of GST enzymes and then incubating them with potentially cancercausing chemicals to see if the enzymes neutralize those substances. Chemicals of interest include acrolein, found in air pollution, heat-treated foods and tobacco smoke. Another substance is a break-down product of 2,4-D, an herbicide associated with lymphoma and bladder cancer in both dogs and people.

Dr. Trepanier acknowledges not all toxic chemicals are avoidable, such as when an owner lives near areas with more air pollution, but owners might be able to minimize their dog’s exposure to some environmental toxins. Further, she said, some chemicals might be neutralized with other treatments.

“This is a big field and we’re just starting to scratch the surface in dogs, but I think we’ll be able to shed some light on what we can do to decrease the chances that healthy dogs like Tucker will develop certain cancers,” said Dr. Trepanier.