A study conducted on nearly 900 dogs identified 12 breeds with an increased risk of brachycephalic obstructive airway syndrome. This condition can negatively affect sleep quality and reduce exercise tolerance in affected animals. The results showed that the list of breeds prone to serious breathing problems is much broader than previously thought.

Characteristics of Brachycephalic Breeds

Dogs with short muzzles and flattened noses are classified as brachycephalic breeds. In recent years, breeds such as French Bulldogs, Pugs, and Pekingese have become especially popular due to their appearance, compact size, and unique personalities. However, selective breeding aimed at enhancing these traits has led to anatomical defects in these animals, including the development of brachycephalic obstructive airway syndrome. Symptoms of this condition include characteristic snoring and wheezing, which owners often mistakenly consider normal, though they actually indicate breathing difficulties.

Causes and Consequences of the Syndrome

The syndrome is caused by anatomical abnormalities: shortened nasal bones, narrowed nostrils, and excess soft tissue in the throat, all of which make it harder for air to reach the lungs. Such dogs tend to sleep poorly, tire quickly during activity, and struggle more in hot weather.

Previously, English and French Bulldogs and Pugs were considered the main breeds at risk for this syndrome. The new study expanded this list to include less common brachycephalic breeds.

Study Details

The study examined 898 dogs from 14 breeds: Affenpinscher, Boston Terrier, Boxer, Cavalier King Charles Spaniel, Chihuahua, Dogue de Bordeaux, Brussels Griffon, Japanese Chin, Maltese, Pekingese, King Charles Spaniel, Pomeranian, Shih Tzu, and Staffordshire Bull Terrier. Each animal underwent a thorough examination, including cardiorespiratory tests and measurements of body and skull structure.

Main Findings

The highest rates of severe breathing disorders were found in Pekingese and Japanese Chins—over 80% of these breeds suffer from the syndrome. The moderate-risk group included Cavalier King Charles Spaniel, Shih Tzu, Brussels Griffon, Boston Terrier, and Dogue de Bordeaux, where 50–70% of dogs showed signs of the syndrome. Only Maltese and Pomeranians showed no breathing problems.

In total, 12 breeds were identified as predisposed to the syndrome: two with the highest risk, five with moderate risk, and the rest with a lower risk.

Anatomical Risk Factors

Data analysis highlighted two main anatomical factors contributing to the syndrome: skull structure (flat face, narrow nostrils, deformed nasal passages, excess soft tissue in the throat) and obesity, which increases the strain on the respiratory system.

Additional Observations

A link was found between tail characteristics and signs of the syndrome: dogs with very short or tightly curled tails experienced breathing problems more often. It is suggested that these features may result from the same anatomical changes, though the exact mechanisms require further study.

Practical Recommendations

Before acquiring a puppy, it is recommended to choose animals from parents who have passed medical screenings and to keep in mind that pronounced physical features—especially a very short, flat muzzle—can negatively impact a dog's breathing and overall health.

The scientific study was published in the journal PLOS One.