Of all the compelling reasons to stop smoking, this one should make pet lovers take notice. There's now ample scientific evidence to suggest that secondhand cigarette smoke can cause numerous health problems in companion animals.

According to the American Lung Association, secondhand smoke contains more than 4,000 chemicals, including 200 that are poisonous and 43 that are known to cause cancer. Research has linked cancer, respiratory illnesses and skin conditions to secondhand smoke in both humans and animals.

Dogs exposed to secondhand smoke are three times more likely to develop lung or nasal cancer than those living in smoke-free homes. A study published in the American Journal of Epidemiology found that dogs in smoking households had a 60 percent greater risk of lung cancer.

Another study published in the journal stated that long-nosed dogs were three times as likely to develop nasal cancer if they lived with smokers. Dogs with long noses (like German shepherds) have a higher risk for nasal cancer and dogs with short noses (like pugs) have a higher risk for lung cancer. This is because, in theory, a dog with a long nose has an extra filtering system, so it is more likely to develop nasal cancer.

Veternarians from Tufts University have found that cats whose owners smoked were three times as likely to develop lymphoma, the most common feline cancer. Cats also have an increased risk of respiratory difficulties such as asthma and respiratory paralysis than those in non-smoking homes.

Animals don't just inhale smoke; the smoke particles are also trapped in their fur and ingested when they groom themselves with their tongues. The Tufts University study also indicates that cats have a much higher rate of an aggressive oral cancer called squamous cell carcinoma. This is likely due to cats being such avid groomers.

Secondhand smoke can literally get under our pets’ skin. Dogs can experience allergic reactions to secondhand smoke such as scratching, biting and chewing on their skin. Owners often confuse this as a reaction to fleas or food allergies.

Our feathered friends are affected by secondhand smoke too. Pet birds can develop eye problems, coughing and wheezing. Birds that sit on a smoker’s hand may experience contact dermatitis due to the nicotine on the smoker’s skin. This can lead to feather picking - an obsessive, destructive behavior whereby a bird plucks, amputates, chews or in some other way destroys some or most of the feathers it can reach with its beak.

Cigarette butts can be just as deadly as secondhand smoke. A puppy ingesting two cigarette butts can die a rapid death due to the toxins in the cigarette butts. An animal drinking water with cigarette butts littered in it can become severely ill or die due to the high concentration of nicotine.

The only effective way to shield your pet and others in your home from the effects of secondhand smoke is to quit smoking. Take measures to limit your pet’s exposure, such as restricting smoking to outdoor areas and washing your hands before handling your pet.

Dr. Kim Vita Hombs, D.V.M., C.V.A. is the owner of Atrium Animal Hospital in Charlotte, NC, whose mission is to promote optimum health and prevention of disease by using an integration of conventional and holistic approaches. She can be reached at 704-542-2000 or AtriumAnimalHospital.com.