BEIJING, Sept. 3 (Xinhuanet) -- Smokers of tobacco not only endanger their family, friends and colleagues, recent research reveals secondhand smoke may increase the cancer risk for their pets, veterinarians say.

    Making the connection of the effects of secondhand smoke on humans to their effects on pets isn't a big one, says veterinarian Carolynn MacAllister of Oklahoma State University.

    "There have been a number of scientific papers recently that have reported the significant health threat secondhand smoke poses to pets," MacAllister said. "Secondhand smoke has been associated with oral cancer and lymphoma in cats, lung and nasal cancer in dogs, as well as lung cancer in birds."

    MacAllister cited a study done by the Tufts College of Veterinary Medicine that showed the number of cats living with mouth cancer was higher for those living in homes with smokers than those who lived in smoke-free environments.

    "One reason cats are so susceptible to secondhand smoke is because of their grooming habits," MacAllister said. "Cats constantly lick themselves while grooming, therefore they lick up the cancer-causing carcinogens that accumulate on their fur. This grooming behavior exposes the mucous membranes of their mouth to the cancer-causing carcinogens."

    Cats living with smokers are also twice as likely to develop malignant lymphoma, a cancer that occurs in the lymph nodes and that is fatal to three out of four cats within 12 months of developing it.

    Studies have also shown that dogs living in a smoking household are more likely to develop cancers of the nose and sinus area, particularly if they are a long-nosed breed, because their noses have a greater surface area that is exposed to carcinogens and a greater area for them to accumulate. Dogs affected with nasal cancer normally don't survive for more than one year.

    Short and medium-nosed dogs are more susceptible to lung cancer, "because their shorter nasal passage aren't as effective at accumulating the inhaled secondhand smoke carcinogens," MacAllister said. "This results in more carcinogens reaching the lungs."

    (Agencies)