Secondhand Smoke and Pets It Harms Pets, Too Secondhand smoke is harmful for everyone in your family, including your pets. Studies have shown that dogs and cats that are exposed to secondhand smoke are at increased risk for cancer. Cats in households with secondhand smoke exposure are almost 2.5 times more likely to develop malignant lymphoma as cats with no exposure. The risk increases to 3.2 times more likely in cats exposed for five or more years. The studies also suggest a link between secondhand smoke and oral cancer, as cats’ mouths are exposed to toxic tobacco smoke residue when they groom their coats. Dogs exposed to secondhand smoke are more likely to suffer from a range of diseases, including asthma, bronchitis and lung cancer, than non-exposed dogs. The shape of a dog’s head plays a role in the types of cancer that are most likely to develop. Long-muzzled dogs, such as collies, are 250% more likely to develop nasal cancer, since their nasal passages have more surface area on which the toxins can accumulate. Breeds with short muzzles are more likely to develop lung cancer and other respiratory diseases. Secondhand smoke is harmful to other pets as well, such as birds or rabbits. Since pets typically spend most of their time inside the home, they’re also exposed to the toxins that cigarette smoke deposits on every surface it comes into contact with. A smoke-free home protects everyone, including pets, from the harmful effects of secondhand smoke, and could even help prevent Catmageddon.