Man’s best friend is helping scientists discover risk factors for cancer. A recent Purdue study found that Scottish terriers exposed to smoke are six times more likely to develop bladder cancer.
The study, led by veterinary oncologist Deborah Knapp, was looking for risk factors for bladder cancer in dogs. The team studies dogs because they cohabit in the same environments as humans.
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Knapp’s team previously found Scottish terriers to be 20 times more likely to develop bladder cancer than other dog breeds. This breed’s predisposition allows researchers to test cancer prevention, detection, and intervention strategies with a smaller sample size than if they tested all breeds at once.
“If we were to do this study with mixed breeds of dogs, it would take hundreds and hundreds of dogs to uncover this same risk,” Knapp said. “Which is probably there, just more difficult to discern because those dogs are not already inclined genetically to get bladder cancer.”
The study tested 120 Scottish terriers less than six years old for bladder cancer over three years. Owners also completed a questionnaire every six months.
The dogs also were checked for cotinine, a byproduct of metabolized nicotine. This would determine if the dog had been exposed to smoke.
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Results found bladder cancer in 32 dogs. Eighteen of these dogs tested positive for cotinine in their urine.
Some of the dogs tested positive for cotinine when their owner didn’t smoke. Researchers believe this could be from exposure outside the home, or from a third-hand exposure, such as having smoke particulates on clothes that the dog breathed in.
Other correlated factors were a history of bladder infections and living near a marsh or wetland. Researchers believe the latter environmental factor may be due to “insecticide spraying or trapped pollutants in the area.”
This study may be widely applicable to additional dog breeds, helping owners create a healthier environment for their pets.
These results can also be a useful model for human cancer risk factor studies, as smoking remains the leading cause of bladder cancer in humans.
