RVC Study Finds Crossbreeding May Reduce Health Problems in Flat-Faced Dogs

A new Royal Veterinary College-led study is adding important evidence to the debate over the health consequences of extreme brachycephalic conformation in dogs, finding that carefully selected crosses involving Pugs were associated with substantially better health outcomes than the purebred dogs studied.

Published in Animal Welfare, the study compared 150 UK pet dogs comprising 51 purebred Pugs, 51 Pug–Jack Russell Terrier crosses, known as Jugs, and 48 Pug–Beagle crosses, known as Puggles. The researchers assessed physical health, respiratory function, body shape, owner-reported quality of life, behaviour and the dog–owner relationship.

The findings suggest that moving away from highly exaggerated facial structure through purposeful crossbreeding may offer a potentially faster route to reducing some conformation-associated health problems.

Longer Muzzles, Better Respiratory Outcomes

One of the clearest differences involved facial structure. The Pug crosses had significantly longer relative muzzle lengths and less severe nostril narrowing than the purebred Pugs. These differences were accompanied by markedly better respiratory assessments.

The study found that all 51 purebred Pugs had some degree of respiratory impairment, with 47.1% classified with severe airway disease. By contrast, all 51 Jugs and 47 of the 48 Puggles were classified as unaffected under the study’s respiratory grading assessment.

The distinction matters because brachycephalic obstructive airway syndrome (BOAS) is closely linked to extreme facial conformation. The researchers note that the risk of BOAS increases as the relative muzzle length becomes shorter.

The study’s respiratory comparison

These findings are striking, but they should be interpreted as results from a relatively small, UK-based observational comparison—not as proof that every crossbred dog will be healthier.

Health Differences Extended Beyond Breathing

The research was not limited to airway disease. Purebred Pugs had significantly higher prevalence of respiratory, eye, skin and musculoskeletal disorders compared with the two crossbred groups. The purebred dogs also accumulated higher veterinary costs.

Vet Times reported median monthly veterinary costs of approximately £45 for purebred Pugs versus £10 for the crossbred dogs in the study.

The researchers also identified substantial differences in physical features associated with brachycephalic health problems, including nostril narrowing and facial proportions. The results reinforce an important principle in canine breeding: body shape is not simply an aesthetic characteristic—it can influence disease risk and welfare.

Crossbreeding Did Not Appear to Erase the Traits Owners Value

One of the more commercially and socially important findings concerns behaviour. A common argument against moving away from breed purity is that changing physical characteristics could also change the behavioural traits and human–animal relationships that make particular breeds popular.

The study found that behaviour profiles and dog–owner relationship measures were broadly similar between the Pugs and the two crossbred groups.

This finding is significant because it challenges the assumption that improving physical health necessarily means losing the behavioural characteristics valued by owners.

The researchers therefore argue that strategic crossbreeding could potentially address welfare problems while retaining some of the characteristics that sustain demand for these dogs.

Why the Findings Matter for Dog Breeding

The RVC team argues that conventional within-breed selection may face a structural limitation in highly extreme breeds.

If most breeding animals already have very similar, highly exaggerated conformations, selecting only within that population may make it difficult to move rapidly toward substantially more moderate body shapes.

Crossbreeding introduces genetic and physical variation from another breed, potentially allowing breeders to move more rapidly toward a less extreme phenotype.

The paper describes brachycephaly as a continuous trait rather than an all-or-nothing characteristic. Relative muzzle length, craniofacial ratio, nostril shape and other facial features vary between individual dogs and breeds, with shorter facial proportions associated with greater BOAS risk.

But This Is Not a Case for “Designer Dogs Are Healthier”

This is perhaps the most important qualification. The study does not establish that crossbred dogs are universally healthier than purebred dogs. It examined three specific groups:

• Pugs

• Pug × Jack Russell Terrier crosses

• Pug × Beagle crosses

It also focused on a defined UK pet population and used a cross-sectional study design. The researchers themselves identify the need for further work.

Therefore, the findings should not be generalised to all designer crossbreeds or interpreted as evidence that simply mixing two breeds automatically creates a healthier dog.

The health benefit appears to be associated with moving away from extreme conformation, rather than with the label “crossbreed” itself. That distinction is critical.

Broader Genetic-Diversity Debate

The study sits within a wider discussion about pedigree breeding, genetic diversity and canine welfare.

The RVC has previously investigated public attitudes towards crossbreeding flat-faced dogs. A separate 2026 RVC-led study published in PLOS ONE found that UK public opinion was divided over whether crossbreeding improves the health, appearance and temperament of brachycephalic dogs.

That research highlighted a major challenge for welfare policy: health information alone may not be enough to change consumer demand when appearance, companionship and established breed preferences remain powerful influences.

The new health study provides another possible approach—offering consumers healthier alternatives that retain some of the characteristics they are seeking, rather than relying solely on campaigns against ownership of extreme breeds.

Potential Shift From Breed Standards to Welfare Outcomes

The implications extend beyond Pugs. Extreme brachycephaly is also seen in breeds such as French Bulldogs and English Bulldogs, and the scientific literature has documented associations between extreme conformation and respiratory, ocular, skin, spinal, reproductive and heat-related problems.

The RVC researchers therefore propose that carefully managed outcrossing or crossbreeding could become one tool within broader breeding strategies aimed at reducing extreme conformation.

This does not mean abandoning breed identity altogether. Rather, it raises a more fundamental question: Should preserving a particular physical standard take priority when that standard is associated with preventable disease and reduced welfare?

That is increasingly becoming a central issue in modern companion-animal breeding.

Bottom Line

The RVC-led research provides some of the strongest recent evidence that purposeful crossbreeding can substantially reduce several health problems associated with extreme brachycephalic conformation—at least in the Pug crosses studied.

The most striking result was respiratory health: all purebred Pugs in the study showed affected breathing, while virtually all Jugs and Puggles were classified as unaffected. But the broader lesson is more nuanced.

Crossbreeding is not inherently a guarantee of better health. Reducing extreme anatomy is the key issue.

The study therefore shifts the debate from “purebred versus crossbred” toward a more useful question: What breeding strategy produces dogs that can breathe, move, see and live comfortably—while retaining the traits people value?

That may prove to be a more meaningful measure of canine breed health in the years ahead.