According to the American Cancer Society, second-hand smoke, also known as environmental tobacco smoke (ETS), is responsible for an estimated thirty-five thousand deaths from heart disease in non-smokers who live with smokers.

It is widely known that cigarette smoke could lead to the development of fatal cancers in both smokers and non-smokers. So what about our pets? Could your second-hand smoke be killing your four-legged friend? "There is very little known about the effects of ETS on animals," notes Dr. Heather Wilson, an oncology specialist at the Texas A&M University College of Veterinary Medicine & Biomedical Sciences
While little may be known about the direct effects second-hand smoke has on pets, there have been several instances where it has been shown to increase the risk of certain cancers in animals."We do know that ETS increases a cat's risk of Squamous cell carcinoma, a type of tumor that occurs commonly in the mouth," says Dr. Wilson. "Laboratory studies using dogs trained to smoke cigarettes have shown that they develop typical lung pathology similar to those in humans, specifically bronchopneumonia, emphysema, fibrosis of the lungs and tumors of the lungs and bronchi."


Even though these studies are old and certainly not condoned by Texas A&M University, these and similar studies seem to show that ETS is harmful to animals. Again, it is important to note that there exists no compelling evidence to suggest that second-hand smoke will inevitably cause cancer. "There are potential links to other tumors in dogs and cats, but no hard evidence to support it as a problem," comments Dr. Wilson. "It is likely one of the many factors that cause cancer, rather than producing a simple cause and effect relationship."

As a veterinary oncology specialist, Dr. Wilson sees numerous patients every day and investigates cancers regularly. When asked if the owner's smoking habits had any direct affect on their pets, she found that there existed no conclusive relationship between the two. However, that does not mean that smoking around pets should continue without concern. "We almost never see anything as a direct result of second-hand smoke," emphasizes Dr. Wilson. "Still, there are cats with asthma that cannot tolerate being around smoke, especially when smoking increases the frequency of asthma attacks. There are also other primary lung diseases that are made worse by cigarette smoking, but there are no tumors that we can specifically say are a direct result of ETS exposure."

Knowing that ETS increases the risk of certain cancers in our furry friends, it is important to understand which animals are more susceptible to cancers.
"Siamese cats are at a greater risk of developing tumors," says Dr. Wilson. "In dogs, the most commonly affected breeds include golden retrievers, German shepherds, rottweilers, boxers and Bernese mountain dogs. However, most pure bred dogs have an increased risk of some form of cancer."

Because ETS could cause certain cancers in our furry companions, it is important to take the necessary precautions when lighting up. Dr. Wilson suggests several preventative measures to take around your pets. "The best thing to do is to stop smoking. It is good for both your health and theirs," urges Dr. Wilson. "Carcinogens are carried on your fingers and around your mouth because of all the oily toxins that are deposited there. The toxins stay in the furniture and carpets for a long time and are impossible to get rid of. These toxins are often the carcinogens of the cigarettes, so stopping smoking all together is the best way to protect yourself and your pet." However, if you can't quit cold turkey, Wilson suggests "smoking outside or in areas away from your pet."

While ETS has not been proven to be a direct cause of cancer in pets, its ability to increase the risk of cancer in our furry companions is hazardous enough. So before you light up another cigarette, think twice about the health of your loving friend and take the necessary precautions to ensure their well-being.