Can Pets Get Cancer from Owners’ Smoking?

By Jennifer Coates, DVM on May 19, 2016

Can Pets Get Cancer from Owners’ Smoking?

By Jennifer Coates, DVM

The Dangers of Second Hand Smoke for Pets

You must have been living on a desert island for the last few decades if you are not aware of the danger that smoking poses both to smokers and to the people who come in contact with second hand smoke. Less well known, however, is the effect that a smoke filled home can have on pet health.

First some definitions. Second hand smoke is smoke that is exhaled or otherwise escapes into the air and can then be inhaled by non-smokers, including pets. Third hand smoke is the residue from smoke that remains on skin, fur, clothing, furniture, etc. even after the air has cleared. Both second and third hand smoke can be referred to using the term “environmental tobacco smoke,” or ETS.

Now let’s take a look at the scientific studies that reveal a link between environmental tobacco smoke and serious diseases in cats and dogs.

The Effects of Tobacco Smoke on Cats

A study published in 2002 demonstrated a greatly increased risk of malignant lymphoma (also called lymphoma or lymphosarcoma) in cats with exposure to ETS. The relative risk for malignant lymphoma in cats with any household ETS exposure was almost 2 ½ times higher than that seen in cats who lived in smoke-free households.

For cats with five or more years of ETS exposure, the relative risk climbed to 3.2. In other words, these poor cats were more than three times as likely to develop lymphoma as were cats who lived in a home where no one smoked.

This study and others also strongly suggest a link between oral cancers in cats and third hand smoke. It is thought that cats groom the toxins contained in tobacco smoke out of their fur, which damages tissues in their mouths. This eventually leads to oral cancer.

The Effects of Tobacco Smoke on Dogs

Dogs can become seriously ill after long term exposure to second and third hand smoke as well. Two studies, one published in 1992 and the other in 1998, determined that cancer of the respiratory tract was more common in dogs who were exposed to environmental tobacco smoke. Interestingly, the type of cancer the dogs got was influenced by the shape of their heads.

The risk of nasal cancer increased by 250% when dogs with long noses (picture a Collie) were exposed to tobacco smoke. On the other hand, dogs with short or medium noses tended to develop lung cancer under similar conditions.

When you think about it, these findings aren’t all that surprising. The extensive nasal passages of long-nosed dogs are good at filtering out the toxins contained in cigarette smoke, which protects the lungs to the detriment of the nose. These same toxins pass right through the relatively shorter noses of other dogs and then become lodged in and damage the lungs.

Many other studies underline the damage that tobacco smoke does to the lining of the respiratory tract and a possible link to non-cancerous diseases such as chronic bronchitis and asthma.

Do Alternatives Help?

By now you might be thinking, “I’ll just smoke outside.” While direct research into the effect that outdoor smoking has on pet health hasn’t been performed, we can look at a 2004 study on infants and draw some conclusions. It found that smoking outside of the home helps but does not eliminate smoke exposure to babies. The infants of parents who smoked outdoors but not inside were still exposed to 5-7 times as much environmental tobacco smoke in comparison to the infants of nonsmokers. Similar results could be expected for pets.

And what about vaping? Again, no direct research into the health effects of second and third hand vaping solution on pet health has been done, but according to the American Lung Association:

In 2009, the FDA conducted lab tests and found detectable levels of toxic cancer-causing chemicals, including an ingredient used in antifreeze, in two leading brands of e-cigarettes and 18 various cartridges. A 2014 study found that e-cigarettes with a higher voltage level have higher amounts of formaldehyde, a carcinogen.

It’s hard to imagine that inhaling substances like these or licking them off their fur could be completely risk free for pets.

Conclusions

Looking at the science brings us to the inevitable conclusion that second and third hand smoke exposure is very dangerous for pets. If you must smoke, do so outside or switch to vaping, but know that you are still likely putting your pets’ health at some degree of risk… to say nothing of what you are doing to yourself.

References

Environmental tobacco smoke and risk of malignant lymphoma in petcats. Bertone ER, Snyder LA, Moore AS. Am J Epidemiol. 2002 Aug 1;156(3):268-73.

Passive smoking and canine lung cancer risk. Reif JS, Dunn K, Ogilvie GK, Harris CK. Am J Epidemiol. 1992 Feb 1;135(3):234-9.

Cancer of the nasal cavity and paranasal sinuses and exposure to environmental tobacco smoke in pet dogs. Reif JS, Bruns C, Lower KS. Am J Epidemiol. 1998 Mar 1;147(5):488-92.

The dog as a passive smoker: effects of exposure to environmental cigarette smoke on domestic dogs. Roza MR, Viegas CA. Nicotine Tob Res. 2007 Nov;9(11):1171-6.

Demographic and historical findings, including exposure to environmental tobacco smoke, in dogs with chronic cough. Hawkins EC, Clay LD, Bradley JM, Davidian M. J Vet Intern Med. 2010 Jul-Aug;24(4):825-31.

Methylation of free-floating deoxyribonucleic acid fragments in the bronchoalveolar lavage fluid of dogs with chronic bronchitis exposed to environmental tobacco smoke. Yamaya Y, Sugiya H, Watari T. Ir Vet J. 2015 Apr 29;68(1):7.

Households contaminated by environmental tobacco smoke: sources of infant exposures. Matt GE, Quintana PJ, Hovell MF, Bernert JT, Song S, Novianti N, Juarez T, Floro J, Gehrman C, Garcia M, Larson S. Tob Control. 2004 Mar;13(1):29-37.

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