The research was a joint effort by the University of Massachusetts School of Public Health and the Tufts University School of Veterinary Medicine. The study found that indoor cats that lived in a home with someone who smoked had a higher incidence of feline lymphoma than cats that live in a non-smoking household.

Feline lymphoma is similar to non-Hodgkin’s lymphoma that affects humans. Cats that are exposed to secondhand cigarette smoke have more than twice the chance of contracting feline lymphoma, which is already one of the most common cancers in cats. In addition, the results of the study show that the longer a cat has been exposed to second hand smoke, the greater the chance that it will develop the disease. Cats that have been subjected to second hand smoke for five or more years are more than three times as likely to develop feline lymphoma as those in non-smoking households.

The results add one more reason to try to quit smoking or to at least smoke outside. Cats and dogs that live inside are not the only ones subjected to passive smoke. Infants and toddlers, as well as older people who don’t leave the home to go to school or work, spend more time in the indoor environment where the second hand smoke remains.