Environmental Tobacco Smoke and Risk of Malignant Lymphoma in Pet Cats
E Bertone, AS Moore. American Journal of Epidemiology August 1, 2002.

Cats living with smokers are almost two and a half times as likely to acquire malignant lymphoma than those in nonsmoking households. Cats not only inhale smoke, they also ingest particulate matter by licking it from their fur while grooming. 180 cats treated at Tufts from 1993-2000 were studied. 80 of these cats were treated for lymphoma and 100 were treated for renal failure [control group]. Duration and level of smoke exposure was related to the rate of lymphoma with cats exposed to smoke for 5 or more years or living with humans smoking a pack or more a day being more than three times as likely to develop lymphoma.