As we already know, secondhand smoke is the smoke that comes from the burning end of a cigarette, pipe or cigar.  It is also the smoke that is exhaled by a smoker.  Only 15% of cigarette smoke is actually inhaled by the smoker-the rest is dispersed into the atmosphere, causing exposure to a potent mixture of over 4,000 chemicals, including over 40 known cancer-causing substances and carbon monoxide.

While much is often said about the dangers of direct smoking and the harmful effects of secondhand exposure to humans, there is also evidence that dogs, cats, and other pets are adversely affected.  Just like their human families, pets can develop respiratory infections, lung inflammation, and asthma when exposed to secondhand smoke.  The sad truth is that many people do not think about their pets.  In a survey, Esure Pet Insurance found that 50% of owners smoke around their pets, but don't realize passive smoking is as harmful to animals as it is to humans.

There are various means by which a pet may come into contact with harmful chemicals contained in tobacco.  Some examples include: by ingestion of cigarette, or cigar butts which contain toxins, by drinking water that contains cigar or cigarette butts (which have high concentrations of nicotine), by breathing secondhand smoke and by ingestion of nicotine replacement gum and patches.

Dogs exposed to secondhand smoke can experience allergic reactions.  Common symptoms of this allergic reaction are the scratching, biting, and chewing off of their skin.  Often time owners confuse this reaction with fleas or food allergies.  Chemicals from cigarette smoke can be found in animals' bodies for a long period of time.  In fact, measurable levels of carcinogens can be found in dogs' hair and urine for months after exposure.

Discarded cigarette butts are very toxic to dogs when eaten and can be fatal.  Just 2 butts, if eaten by a puppy, can cause death in a short period of time.  Dogs that inhale secondhand smoke are three times more likely to develop lung or nasal cancer than dogs in a smoke-free home.  Studies have shown that dogs living in a smoking household are susceptible to cancers of the nose and sinus area, particularly if they are a long-nosed breed because their noses have greater surface area that is exposed to carcinogens and a greater area for them to accumulate.  Dogs affected with nasal cancer normally do not survive for more than one year.  Warning signs of nasal cancer include swelling over the nose or sinus area, sneezing and bloody nasal discharge.

Short and medium-nosed dogs are more susceptible to lung cancer, "because their shorter nasal passage is not as affective at accumulating the inhaled secondhand smoke carcinogens.  This results in more carcinogens reaching the lungs.  Warning signs of lung cancer in dogs include chronic coughing, weight loss and abnormal fatigue.

Cats that live with cigarette smokers are twice as likely to develop feline lymphoma, a deadly cancer of the blood and immune system.  On average, the survival of a cat with lymphoma is 6 months.  In addition, they are twice as likely to develop malignant lymphoma, a cancer that occurs in the lymph nodes and that is fatal to 3 out of 4 cats within 12 months of developing it.  Other types of cancer that cats are at risk of developing include intestinal cancer and squamous cell carcinoma (a type of oral cancer commonly found in smokers) most likely because the carcinogens in smoke can settle on the cat's fur and the cat can pick them up as it grooms itself.  This grooming behavior exposes the mucous membranes of their mouth to the cancer-causing carcinogens.

Birds can experience adverse reactions to secondhand smoke and may develop eye problems, as well as other respiratory problems like coughing and wheezing.  In addition, birds that sit on a smoker's hand can experience contact dermatitis from the nicotine that remains on the smoker's hand which can cause them to pull out their feathers.  Birds are at risk for lung cancer, as well as pneumonia, because their respiratory systems are hypersensitive to any type of air pollutant.

Other pet studies have shown similar results.  For example, a study exposing hamsters to doses of cigarette smoke demonstrated that the inhalation of secondhand smoke inhibits their reproduction.  Passive smoke has also been shown to significantly increase blood pressure in rabbits.

Giving up smoking will not only improve the smoker's health but their animal's health too, and can even cut down vet costs.  If a smoker must smoke please do it outside or away from other humans and animals.  Keep ashtrays clean-Don't leave butts in them for pets to find and dispose of nicotine gum and patches in receptacles that aren't pet accessible.  If we remind smokers of the benefits of quitting not just for them, but others as well, it just may be the added incentive they need to quit for good.