Scottish terriers exposed to cigarette smoke at home were six times as likely to develop bladder cancer as their counterparts in nonsmoking homes, a recent analysis found.

The long-term study, published in the Veterinary Journal, followed 120 Scottie dogs over three years. The breed is known for its high rates of bladder cancer: Scottish terriers have 20 times the risk of most other breeds, and most dogs that do get bladder cancer have the most invasive form of the disease.

Researchers used surveys from dog owners and analyzed the dogs’ urine to look for a nicotine metabolite that indicates exposure to cigarette smoke. During the study period, 32 dogs developed bladder cancer.

Scottish terriers that lived in homes with smokers were six times as likely to develop cancer than controls, with seven of the 32 dogs with bladder cancer living with smokers. Urinalysis revealed that the dogs living with smokers were exposed to an average of 10 years’ worth of pack-a-day smoking, compared with 1.5 years’ worth of pack-a-day smoking for dogs that didn’t get cancer.

Another significant risk was living within a mile of a marsh or wetland — areas that can trap pollutants or be treated with insecticides. Dogs that lived near marshy land were 21.23 times as likely to develop bladder cancer than controls. Older age and a history of past urinary tract infections were also associated with higher cancer risk.