Are pets affected by second-hand smoke?

New University of Saskatchewan research -- soon to be peer-reviewed -- suggests there are measurable changes in the heart and blood vessels of dogs exposed to second-hand smoke in the home. In humans, such changes are a precursor of cardiac disease.

"Our pets are being affected," says Lynn Weber, assistant professor at the U of S Western College of Veterinary Medicine (WCVM).

"Next we want to figure out what are the consequences of these effects."

Veterinary medicine student Tim German led the study. He and Weber, his supervisor, hope to submit their findings for publication this winter.

German is a Merck-Merial veterinary scholar, a drug company-sponsored program that provides vet students the opportunity to do research during the summer.

He presented the findings at a poster session at this summer's Merck-Merial symposium in Baton Rouge, La.

"We were looking for a possible link between canine health and cigarette smoke exposure," German says.

"The results suggest exposure to cigarette smoke causes structural and functional cardiac changes in dogs."

The study looked at two sets of dogs: six from smoking homes and eight from non-smoking homes.

The healthiest dogs based on age, weight and body condition were used.

To determine the health of the dogs, German used a variety of methods -- from pet owner questionnaires to complete physical examinations of the dogs, including blood tests and ECGs (electrocardiograms).

"We wanted to look at everything," he says.

"We went from tip to tail. If you could look at it, we were going to look at it."

German relied on his experience as a first-year vet student and years of volunteering at WCVM and other clinics around Saskatoon.

Ultrasound measurements of the heart showed that dogs from smoking households had more muscle on the left side of the heart.

This can be a sign of high blood pressure because the heart has to pump harder in order to distribute the blood to the body.

While extra heart muscle is sometimes seen in very athletic dogs, the questionnaire showed each of the dogs had similar fitness levels.

"They were pretty much couch-potato dogs in both groups," German says.

German also used flow-mediated dilation, an ultrasound procedure for viewing arteries in human medicine that permits measurement of artery relaxation.

According to Weber, this is likely the first time this procedure has been used in a veterinary context. The flow-mediated dilation revealed that dogs from smoking homes have decreased relaxation in their arteries, another potential indicator of high blood pressure.

Blood pressure was not directly measured in the dogs because typical methods used to test blood pressure in humans are less reliable with pets.

Next summer, German and Weber will focus on second-hand smoke effects on blood pressure in dogs using specialized equipment.

Though there were detectable changes in the dogs' cardiovascular system, German notes the changes occur without signs of sickness in the dog.

In humans who smoke, these same indicators frequently lead to cardiac disease.