Second-Hand Smoke Is Causing Bladder Cancer in Dogs, New Study Finds

This just in: second-hand smoke, still bad.

July 12, 2024

We’re a long way from the Marlboro Man pushing cigarettes as some ideal form of independence and strength. And Joe Camel — the ubiquitously recognized, nicotine-schilling cartoon camel — got killed off by tobacco marketers in 1997. Thanks to increased awareness of the damage they produce, cigarette sales have steadily plummeted over the past couple of decades. The once-common image of cigarette smoke hovering outside of bars and restaurants has now been replaced by vape pens, which seems like a lateral move, aesthetically speaking.

But while vaping may look ridiculous, it avoids one massive problem that cigarettes create: second-hand smoke. It’s an issue that puts everyone around in danger and we’re still learning the true extent of its impact. Now, there is even research sending a stark warning to pet parents everywhere who enjoy ripping analog cigs.

Specifically, one study out of Purdue University this year connected exposure to second-hand smoke with an increased risk of bladder cancer in dogs. Led by veterinary oncologist Deborah Knapp, the Purdue team tracked 120 Scottish Terriers over three years to suss out the impact of their housemates’ tobacco habits.

Second-hand smoke raises cancer risk.

To determine which animals endured cigarette smoke-filled environments, the researchers relied on two primary methods beginning with surveys given to participating pet parents. They then cross-referenced these responses with urinary analyses performed on the dogs who looked for a nicotine metabolite known as cotinine, which would indicate exposure to cigarette smoke. Through these surveys, the team also assessed food intake, activity, and location as cancer factors.

“Cancer is a combination of what you are born with — your genetics — and what you are exposed to — your environment,” Knapp explained in a statement. “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?’”

In the end, 32 total Scottish Terriers developed bladder cancer during the three-year testing period. Of those 32 pups, seven lived with regular cigarette smokers. Knapp and her team determined that dogs residing with smokers were six times more likely to develop cancer compared to those in smoke-free environments. In fact, the urine analysis indicated that these dogs were, on average, exposed to the equivalent of 10 years of smoking one pack a day. So if you were looking for a final push to kick your smoking habit, there you go.

While the number of regular cigarette smokers has dipped nearly 50 percent from 2005, it’s hard to overstate how massive that statistic was to begin with. As a result, a significant percentage of U.S. adults still smoke cigarettes even after the huge drop. According to the CDC, over 28 million Americans currently smoke cigarettes. Considering that around 60 million households have at least one dog, it’s not hard to envision some massive crossover. For those folks, Knapp is optimistic her team’s findings will inspire them to quit for good.

“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 said. “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.”

Unfortunately, if you’ve never touched tobacco in your life your pet may still be in danger of inhaling the hazardous fumes. The Purdue researchers discovered even the dogs who did not develop bladder cancer had the chemical equivalent of being exposed to over one year of pack-a-day smoking on average. As Knapp notes, second-hand smoke can come from a variety of unexpected sources and linger much longer than most presume.

“If someone goes out to a smoky concert or party, then comes home and their dog hops up on their lap to snuggle with them, the dog can be exposed to the particulate material in smoke through the person’s clothing,” she added.

One breed fits all?

The only possible hole in Purdue’s study is that it involved merely one breed, Scottish Terriers. However, that was very much by design and not just because it was partially funded by the Scottish Terrier Club of America. Knapp explained that the breed is genetically prone to developing cancer, especially bladder cancer. To be exact, the Purdue statement adds they’re up to 20 times more likely to get the disease than other breeds.

It’s this genetic link that the study’s author believes allowed her researchers to isolate other factors that can affect cancer risk without massively expanding the number of pets involved in testing. Beyond that, she feels confident the impact of second-hand smoke is similar for dogs of all breeds.

“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 said.

Of course, the dogs in smoking households weren’t the only ones to get cancer. Some who had little exposure to second-hand smoke wound up getting the disease anyway. But it is the factor most in the control of pet parents. So, if you’re a cigarette-smoking dog parent, ditching the darts for good remains the best action plan. Or, Lord help me, take up vaping (don’t do that, either).

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Sean Zucker

Sean Zucker is a writer whose work has been featured in Points In Case, The Daily Drunk, Posty, and WellWell. He has an adopted Pit Bull named Banshee whose work has been featured on the kitchen floor and whose behavioral issues rival his own.