“Smoke Gets in Your Eyes” (and lungs): Second-hand Smoke

Feb 29, 2016

Did you know cats and dogs also suffer from second-hand smoke effects just like people?  It has been established in human medicine since the late 1970’s that second-hand smoke is enough to damage the lungs of people around a smoker.  

Exposure is greatest in enclosed areas like apartments and cars. High frequency of smoking in the home increases the toxic load on a pet’s lungs. Sources of smoke such as unfiltered cigarettes, marijuana, pipe smoke, and cigars or cigarillos have more tars and particulates than filtered cigarettes.

Cats are especially sensitive. Cats can develop asthma, similar to human asthma, and those cats living in homes where  there are heavy smokers are more likely to develop chronic bronchitis as well.

Second-hand smoke produces chronic irritation in the lining of the airways. Smoke contains potent carcinogens as well, so inhaling smoke can cause cancer in pets too! Airways exposed to smoke over time will undergo dysplasia. This means the lining cells of the airways become abnormal. The airway cells can transform into cancer cells if subjected to long-term heavy exposure to  smoke. Smoke can also trigger reactive airway syndrome. Lymphoma risk in cats increases with exposure, and lung and nasal cancer are most common in the dog, but increased risk for transitional cell cancer of the bladder in dogs has also been proposed.

There are 42 harmful components in smoke so it is a complex substance. See the article Smoke Inhalation Injury to learn more about heavy acute exposure to smoke, such as occurs in house fires.

In a 2007 study, researchers found evidence of nicotine, coti-nine and NNAL (a metabolite of the carcinogen nitrosamine methynitrosamino pyridyl butanone) in the urine of the cats exposed to environmental tobacco smoke. This shows that these harmful compounds are absorbed and can therefore target organs distant to the respiratory tract.   

There is a new risk to pets from e-cigarettes. Though they do not produce smoke, the nicotine in the solution in the cartridge is aerosolized into small particles so pets should be kept away from the vapors to prevent inhalation. Toxicity is very likely if the pet eats the liquid contents of the vial itself. The refill containers are even more dangerous as they contain multiple vials. Flavoured liquid is particularly attractive to dogs. A vial’s contents is enough to cause signs in large dogs and death in small dogs or cats so great care should be taken to prevent access to these. If the pet is found to have chewed or swallowed vials or refill packs this is an emergency and the pet should be taken to the clinic immediately to start receiving care. 

Nicotine is very toxic when sudden exposure occurs, and as in the traditional source of nicotine exposure by eating cigarettes or butts, the pet will experience vomiting, depression or anxious behaviour, fast heart and breathing rate, and may develop tremors, seizures, and sometimes death occurs.

The bottom line for good health is to keep your pet well away from all smoke and vapor sources—your pets rely on you! 

(February 2016)


2007 AJVR, vol 68, No 4 pp 349-353, McNeil, E.A. et al doi: 10.2460/ajvr.68.4.349