New research from the Royal Veterinary College has revealed that crossbreeding extreme brachycephalic (flat-faced) Pugs with non-brachycephalic dog breeds can substantially improve health and welfare outcomes in the offspring, while preserving many of the behavioural traits and close owner-dog relationships that contribute to the purebred Pug’s breed’s popularity.

Brachycephalic dogs, including Pugs, remain highly sought after in the UK despite growing evidence linking their extreme body shapes to severe and lifelong health problems, including breathing difficulties, eye disease, skin-fold infections and heat intolerance. Previous efforts to tackle these issues within selective breeding programmes have largely focused on breeding between purebred Pugs who have a lower disease burden to maintain ‘purity’, while retaining the purebred breed’s distinctive body conformation. However, any welfare improvements from this approach have been slow to achieve, as offspring largely retain the extreme body shape that causes the associated health problems. Thus, global interest has shifted towards crossbreeding the extreme purebred parent breed (e.g Pug) with a non-extreme, non-brachycephalic breed (e.g Jack Russell Terrier or Beagle) to create offspring with more moderate body shapes that face reduced disease burden, while retaining their desirable qualities.

Therefore, the study, led by researchers from the RVC alongside collaborators from Paragon Veterinary Referrals, EviVet Evidence-Based Veterinary Consultancy and Blue Cross, compared 150 UK pet Pug and Pug-crossbreed dogs recruited between November 2023 and September 2024. All dogs underwent in-person veterinary assessment for the presence of respiratory, eye, dental, skin and neurological disorders. Dogs also underwent Respiratory Function Grading Scheme (RFGS) assessment, an established method to grade the presence and severity of Brachycephalic Obstructive Airway Syndrome.

Owners also completed detailed questionnaires covering their dog’s health history, veterinary costs, exercise and maintenance requirements, behaviour, quality of life and owner-dog relationship. The body shape of each dog was assessed, including skull shape, nostril size, eye shape, the presence of nasal folds and tail length and shape.

The findings revealed major improvements in the overall health of the Pug-crossbred dogs compared to purebred Pugs. Nearly half (47.1%) of purebred Pugs were diagnosed with severe airway disease and all were graded as having affected breathing, whereas all Jugs (Pug × Jack Russell Terrier) and all but one Puggle (Pug x Beagle) (97.9%) were graded as unaffected. The Jugs and Puggles also showed substantially longer relative muzzle length than Pugs, which was found to be strongly associated with lower odds of respiratory disease in statistical analyses. Both breeds also showed fewer conformational health problems and substantially lower veterinary costs compared with purebred Pugs.

Additional findings include:

• Severe nostril narrowing was only identified in the purebred Pugs, affecting more than one in five (21.6%) dogs studied.
• All purebred Pugs had nasal skin folds, compared with only 15.7% of Jugs and 27.1% of Puggles. Consequently, 38.3% of Pugs were affected by nasal fold dermatitis, but was absent in Puggles and only affected 2% of Jugs.
• Purebred Pugs were significantly more likely to be reported by their owners to have breathing, heat regulation and exercise problems (51% compared to 2% of Jugs and 4.2% of Puggles).
• Purebred Pugs were significantly more likely to show eye abnormalities including turned-in (entropion) and turned-out (ectropion) eyelids.
• Jugs and Puggles showed significantly fewer orthopaedic and neurological abnormalities during clinical assessment.
• Veterinary costs were substantially higher for purebred Pugs, with median monthly veterinary costs more than four times those of the Pug-crossbred dogs - £45 per month for Pugs compared with £10 for Jugs and Puggles.
• Owners of Jugs and Puggles were more likely to rate their dogs’ quality of life as “excellent” - 92.2% of Jugs, 81.2% of Puggles, compared with 58.8% of purebred Pugs.
• Behaviour profiles and owner-dog relationship scores remained broadly similar between the purebred and crossbred dogs.

The study also found that the dog-owner bond did not differ between Pugs, Jugs and Puggles. Furthermore, there were a few major behavioural differences between the groups, with an improvement in trainability in the crossbreeds compared to purebred Pugs.

These findings therefore suggest that deliberate crossbreeding away from extreme body shapes in breeds such as Pugs could offer a rapid and practical route to improving canine welfare while protecting what owners love most, with these benefits possible in only one generation.

Dr Rowena Packer, Senior Lecturer in Companion Animal Behaviour and Welfare Science at the RVC and senior author of the paper, said: “Improving the welfare of dogs with extreme conformations is one of the biggest challenges facing the canine welfare community globally. This study provides evidence that moving away from extreme body shapes by shedding the shackles of breed ‘purity’ can offer a rapid and effective pathway towards innately healthy companion dogs.

“If international kennel clubs and breeders are serious about tackling the high disease burden in breeds with extreme conformation, carefully managed crossbreeding programmes should be recognised as one of the most effective tools available for improving canine welfare.”

Elizabeth Youens, Master’s student at the RVC and first author of the paper, said: “Our findings suggest that improving the welfare of brachycephalic dogs does not have to come at the expense of the qualities owners value most. The Jugs and Puggles in this study showed markedly better health outcomes than purebred Pugs while maintaining similar behaviour profiles and strong owner-dog relationships. Purposeful crossbreeding away from extreme body shapes is now shown as offering a practical route to improving canine welfare.”

Ashleigh Brown, Scientific and Policy Manager at the RSPCA, said: "The RSPCA remains deeply concerned about the welfare impact of breeding dogs with unnatural features that cause both physical and psychological harm. These findings demonstrate that significant improvements in canine health and quality of life are achievable through judicious out-crossing - findings that should be welcomed sector-wide and implemented in breeding decisions.  Canine welfare must always take precedence over aesthetics, and both responsible breeding and informed consumer choices when purchasing a pet will be powerful drivers for change. We urge prospective owners to prioritise health by choosing dogs with moderate, functional features that support a high quality of life."

The research was funded by the Animal Welfare Foundation, Blue Cross and the RSPCA.