Study finds cigarette exposure to Scottish terriers can increase risk of bladder cancer


Researchers concluded that cigarette smoke exposure can increase odds of Scottish terriers developing bladder cancer by 6 times



A recent study conducted by Deborah Knapp, DVM, MS, DACVIM-Oncology, and a team of investigators that published in The Veterinary Journal found Scottish terriers exposed to cigarette smoke were at a higher risk of developing bladder cancer. The study found that Scottish terriers exposed to cigarette smoke were 6 times more likely to develop bladder cancer than those who were not exposed.1

“We know that Scotties’ genetics play a huge role in making them vulnerable to cancer,” said Knapp, in an organizational release.2 “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, which is probably there, just more difficult to discern because those dogs are not already inclined genetically to get bladder cancer.”

Knapp’s team studied a cohort of 120 Scottish terriers over 3 years. The team assessed the activity, environment, food, health, locations, and anything else they could think of that could affect the pet’s cancer risk.2 The research team also joined forces with Marcia Dawson, DVM, Purdue alumna, and Scottish terriers breed champion, to learn more about these dogs to help understand what the research could reveal.

According to the release, when dogs, or even humans, are exposed to tobacco smoke whether licking it off clothes or breathing it in, the body takes the chemicals found in the smoke and then eliminates them through urine. Because of this, it can lead to the development of cancer in the urinary tract as well as a way researchers can assess smoke exposure. The study researchers analyzed the urine of the Scottish terriers for nicotine metabolite, cotinine, and its presence indicated that the canine was exposed to significant amounts of tobacco smoke.

“Cancer is a combination of what you are born with — your genetics — and what you are exposed to — your environment,” Knapp explained.2 “In this case, we studied these dogs for years at a time, and then we went back and asked, ‘What was different between those that developed cancer and those that did not develop cancer? What were the risk factors?’”

Knapp and her team stressed that this discovery is not new, it just provided new information that can be used to better protect pets moving forward. One interesting finding the study brought to light was there was no link between lawn chemicals and bladder cancer, which previous studies have found to be true. Knapp believes that the results reached this conclusion because pet owners are more aware of the lawn chemicals risk, so they took necessary precautions.

“What we hope pet owners will take from this is that if they can reduce the exposure of their dogs to smoke, that can help the dogs’ health,” Knapp concluded. “We hope they stop smoking altogether, both for their health and so they will continue to be around for their dogs, but any steps to keep smoke from the dogs will help.”

The study's researchers hope that these findings find more ways that pet owners can protect their dogs by reducing the amount of smoke around the dog, smoking outside, or even changing their clothes before coming home from a smoky environment. They also wanted to remind readers that the results are not black and white with some dogs living with someone who smokes not developing cancer and vice versa.

The study was funded by the Scottish Terrier Club of America, National Institutes of Health’s National Cancer Institute, and gifts made to Purdue in the name of canine bladder cancer research.


  1. Knapp DW, Dhawan D, Ruple A, et al. Association between cigarette smoke exposure and urinary bladder cancer in Scottish terriers in a cohort study. The Veterinary Journal. 2024;303(106044):106044. doi:10.1016/j.tvjl.2023.106044
  2. Exposure to cigarette smoke increases cancer risk in dogs. News release. Purdue University. January 3, 2023. Accessed January 4, 2023.
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