Brachycephalic Dog Breeds: Breathing Problems Linked to Flat Faces

Many dog owners are drawn to the charming, “squished” faces of breeds like pugs, bulldogs, and Pekingese. However, a growing body of research highlights a serious health consequence of this intentionally bred facial structure: breathing difficulties. A study published on February 18, 2026, in PLOS One, adds to the evidence linking shortened skulls to chronic respiratory problems in dogs, a condition known as Brachycephalic Obstructive Airway Syndrome, or BOAS.

Brachycephaly refers to a skull shape that is significantly shortened, resulting in a flattened face. While aesthetically appealing to some, this conformation can lead to a narrowing of the airways, making it difficult for affected dogs to breathe easily. Symptoms of BOAS include noisy breathing, exercise intolerance, and, in severe cases, the need for surgical intervention.

The recent study, led by Francesca Tomlinson from the University of Cambridge, United Kingdom, examined nearly 900 dogs across 14 breeds, including Boxers, King Charles Spaniels, Chihuahuas, and Pomeranians, in addition to the more commonly recognized brachycephalic breeds. Researchers meticulously measured the dogs’ skulls, noses, bodies, and necks, and assessed them for signs of BOAS. Dogs were graded on a scale of zero to three, with zero indicating minimal symptoms and three representing significant breathing difficulties that impacted exercise and overall well-being.

The findings revealed a wide variation in the prevalence of BOAS across different breeds. While Boxers and Staffordshire bull terriers showed relatively low rates of respiratory issues, Pekingese and Japanese chins were found to be at particularly high risk, exhibiting similar rates of breathing problems to bulldogs and pugs. Specifically, only 11 percent of Pekingese were found to be free of BOAS symptoms, compared to approximately seven percent of pugs.

According to the study, the primary factors contributing to airway obstruction were the degree of facial flatness, the narrowness of the nostrils, and the dog’s weight. These physical characteristics directly impact the ability of air to flow freely through the respiratory system.

“The risk [of the condition] varies quite significantly across the different breeds,” Tomlinson says. The research builds upon existing knowledge of BOAS in pugs and bulldogs, expanding the understanding of the condition’s prevalence and contributing factors across a broader range of breeds.

Dan O’Neill, an animal epidemiologist at the Royal Veterinary College in London, emphasizes the underlying cause of the problem. “This study confirms much of what the science and biology has known for decades,” he states. “Artificially selecting dogs for unnaturally short skulls reduces the ability of these dogs to breathe, sleep, exercise and live a complete canine life.”

The implications of these findings extend beyond simply identifying at-risk breeds. Researchers suggest that the scoring system used in the study could be a valuable tool for breeders, allowing them to select for dogs with less exaggerated facial features and, improved respiratory health. The study also notes a potential shift in breeding practices, with data from bulldogs and pugs suggesting that breeders may already be selecting for less severely affected individuals, potentially leading to healthier populations.

The study’s findings underscore the importance of considering the health implications of breeding for specific physical traits. While the aesthetic appeal of brachycephalic breeds is undeniable, prospective dog owners should be fully aware of the potential respiratory challenges these dogs may face. Understanding the risks associated with BOAS can help owners provide appropriate care and advocate for responsible breeding practices that prioritize the health and well-being of these beloved companions.

Further research is needed to fully elucidate the physiological and genetic mechanisms underlying BOAS in different breeds. However, this study provides a crucial step forward in understanding and addressing this significant health concern in brachycephalic dogs.