Does exposure to air pollution during early gestation increase our risk of heart disease? The answer appears to be yes—both for humans and for some of our closest animal companions—according to several studies led by Mary Regina Boland, PhD.

Dr. Boland’s latest research on the subject, published in Nature Scientific Reports, compared birth-month-related risks for dog breeds that are predisposed to heart disease and for those that are not. Among the first group, birth month made little difference in rates of heart disease. But in the second, researchers found a clear birth-season relationship, which climaxed during the period from June to August. The comparison between the two groups led the team to conclude that overall, the risk of developing heart disease later in life is significantly higher for dogs born in the summer months—when fine-air particulates, such as those found in pollution from factories, also peak.

In previous studies, Boland and others have found similar results in humans, and the latest findings add to that evidence.

“It’s important to study dogs for several reasons,” said Dr. Boland. “The canine heart is a remarkably similar model to the human cardiovascular system. Also, because they are divided by breed, it is easier to sort out among dogs whether they are predisposed to heart disease or not.” The short gestational period for dogs—just two months—provides a handy model for early gestation in humans, she added. Last, the environmental factors are similar as well. “Humans and dogs share their lives together and are exposed to similar environmental effects. Taking all of these factors into account, seeing the birth season-cardiovascular disease relationship in both species illuminates the mechanisms behind it.”

The team, which also included members from Penn Vet, obtained data from the Orthopedic Foundation of Animals on 129,778 canines, which represented 253 distinct breeds.

The researchers note that future studies may be valuable to probe why specific breeds are more susceptible to cardiovascular disease and to explore how birth season affects later risk of other birth-month dependent diseases (e.g., certain neurological conditions and reproductive conditions).