We bred flat-faced dogs into suffering. New science says we can breed them back out.

Doges Editorial · 2026-05-18 · 5 min read

We bred flat-faced dogs into suffering. New science says we can breed them back out.

French bulldogs are now America's most popular breed — and most of them struggle to breathe. A new Royal Kennel Club study shows their respiratory problems are significantly heritable, meaning selective breeding could turn this around.

Spend an afternoon at a dog park and do an informal count. Chances are, at least one in five dogs you see is a French bulldog — or a pug, or an English bulldog — with the compressed face, the wrinkled brow, the enormous round eyes, and the breathing that sounds like a small engine struggling against something it can't quite clear. It's audible from ten feet away on a warm day. French bulldog owners know the sound so well they have a name for it: just "the breathing." Since 2022, the French bulldog has been the most popular breed in America, ending the Labrador retriever's thirty-three-year reign at the top.

It is also a breed that routinely labours to breathe. And the question of whether we can do something about that — whether millions of flat-faced dogs can be kept both beloved and healthy — is at the centre of a new study published May 13, 2026, in PLOS One. The researchers, led by geneticists at the Royal Kennel Club, have produced the clearest genetic evidence yet that the answer is yes.

The anatomy of a crisis

The clinical name is brachycephalic obstructive airway syndrome — BOAS. The mechanism is straightforward and grim: flat-faced breeds have been bred for shortened skulls, but the soft tissue inside the skull doesn't shrink proportionally. The nostrils narrow. The soft palate grows too long and folds into the airway. The trachea may be too small. The result is a permanent bottleneck — the dog's breathing apparatus working overtime just to move air through passages that are structurally too tight.

In mild cases, this means a dog that snores, tires quickly, and needs shorter walks in warm weather. In severe cases — and severe BOAS is more common than most new owners realize — it means a dog that requires surgery before the age of two, that cannot safely ride in a car in summer, and that can go into respiratory distress during what looks like moderate exercise. Insurance companies have begun declining coverage for the condition. Yet despite the severity and the awareness, demand for flat-faced breeds has kept rising. Researchers studying this gap have given it a name: the brachycephalic crisis.

What the new study found

The PLOS One study took a different angle than previous BOAS research. Rather than measuring how prevalent the condition is, the Royal Kennel Club team asked a genetics question: how much of the variation in respiratory function between individual bulldogs, French bulldogs, and pugs is due to hereditary factors? They scored dogs on the traits most tightly linked to BOAS — respiratory function, nostril size, body weight — and ran heritability analyses.

The results were encouraging in a specific, actionable way. Respiratory function was found to be 21 to 49 percent heritable. Nostril size came in at 31 to 39 percent heritable. Crucially, these traits tend to travel together: a dog selected for better breathing tends also to have larger nostrils and a healthier weight. That co-heritability is good news, because it means breeders don't need to trade off one health trait against another — improving the most important one tends to lift the others.

Our findings provide clear evidence that respiratory health in these breeds is influenced by genetic differences between dogs, and importantly, that improvement is achievable through selective breeding. By using objective tools like the Respiratory Function Grading Scheme, breeders can make more informed decisions that prioritize health, helping to reduce the prevalence of BOAS over time.

— Dr. Joanna Ilska, study author and geneticist, Royal Kennel Club

Why we keep buying flat-faced dogs

It is worth asking, without being smug about it, why French bulldogs became so popular in the first place — and why that popularity keeps rising even as awareness of BOAS spreads. The short answer is that flat-faced dogs are extremely cute. The more accurate answer is that they are cute in a way that is specifically and powerfully compelling to the human brain.

The features that define a French bulldog — shortened muzzle, tall domed forehead, large front-facing eyes — match the proportions of a human infant face. Researchers call this the "kindchenschema" or baby-schema effect: our nervous systems are wired to respond to infant facial features with a surge of protective, nurturing instinct, because that response is evolutionarily critical. Knowing this doesn't make the feeling go away. It does explain why consumer education alone has proven insufficient to reverse the brachycephalic crisis. We are fighting biology with pamphlets.

Which is precisely why a genetics-based breeding intervention matters. If the animals themselves can be made healthier over a few generations — without dramatically changing the appearance that drives demand — the crisis doesn't require a revolution in human taste. It requires consistent, measurable decisions at the breeder level.

The tool that breeders already have

The Royal Kennel Club has been running a Respiratory Function Grading Scheme since 2012. Dogs are assessed by veterinary specialists and given a score on a four-point scale based on how easily they breathe during and after moderate exercise. Dogs that score well — breathing without obvious effort, recovering quickly — are considered suitable breeding candidates. Dogs that score poorly are flagged as unsuitable for breeding until the condition is addressed.

The scheme is voluntary, and uptake has been uneven. The PLOS One study provides the genetic justification for making it standard. If breeders consistently select dogs with better respiratory scores over several generations, the average breathing capacity of the breed rises — not because a single dog was dramatically changed, but because the distribution of genetic variation within the breed gradually shifted. This is the logic of artificial selection, which shaped every modern breed; it can be pointed toward health as readily as toward aesthetics.

What to watch for on your walks

If you share your life with a French bulldog, a pug, or an English bulldog, you already know their breathing in granular detail. You have learned to read what's normal for your specific dog. The difference between the background snore of a healthy flat-face at rest and the laboured, open-mouthed breathing that means this walk should end — that's a distinction you've internalized without anyone teaching it to you.

Dogs with BOAS tend to show their clearest signals during activity: a pace that slows earlier than usual, more rest stops, a reluctance to go at all in humid weather. These are not character traits — they are respiratory data. Tracking them over time, even informally, gives both you and your vet real information about whether things are stable or changing.

The PLOS One study closes with a line that lands differently when you think about the specific dog in your life: "We bred them into this predicament, maybe we can breed them out of it, too." That is both a challenge to the breeding community and a kind of quiet optimism — the idea that the relationship between humans and dogs is not just capable of going wrong, but of being corrected. We have been shaping these animals for ten thousand years. We can shape them toward health.