In a study published by the American Journal of Epidemiology in August, the first link between cigarette smoke and feline lymphoma was established. Although the focus of the study originally was not to hone in on this information, this conclusion was too obvious to overlook: that cats living with smokers were at least twice as likely to acquire malignant lymphoma than those in nonsmoking households.

The study was researched by epidemiologist Dr. Elizabeth R. Bertone of the University of Massachusetts, along with veterinarians Drs. Anthony S. Moore and Laura Snyder from the Tufts University College of Veterinary Medicine. The report, titled “Environmental Tobacco Smoke and Risk of Lymphoma in Pet Cats,” is the first of its kind. The independent linkage of feline sarcomas to second-hand smoke from cigarettes debunked a once widely held belief that feline sarcoma is a byproduct of the feline leukemia virus.

Feline lymphoma is the most common cancer type in cats, often involving the abdominal organs and the nasal cavities. The study involved 180 cats treated by the Tufts University Veterinary Teaching Hospital between 1993 and 2000. Adjusting for age and other factors, the study showed that the relative risk for lymphoma in cats was 2 1/2 times that of cats that were in nonsmoking households. To take the point further, cats that had been exposed to heavy smokers in a household (more than a pack a day) for over five years became affected by lymphoma by more than triple the rate of nonsmoker households.

The number of household smokers also appears as a factor with nearly a double relative risk for cats living in households with one smoker, but a risk of four times in those environments with two or more smokers vs. the nonsmoking households.

It was pointed out in the study that inhaled smoke was not the only risk by cats in this cancer study. Cats also inhale particulate matter off their fur as they groom themselves.