Noisy breathing in flat faced dogs is never normal – new research proves selective breeding can change that

New research published confirms that breathing problems in pugs, French bulldogs and bulldogs are heritable, and that selective breeding can meaningfully reduce how many dogs are affected.

The study was co-authored by Jane Ladlow, European and RCVS Specialist in Small Animal Surgery and a founder of Granta Veterinary Specialists (GVS) in Cambridge.  She is Chief Assessor of The Royal Kennel Club / University of Cambridge Respiratory Function Grading Scheme (RFGS) and devised the RFGS with colleagues at Cambridge University. Launched in 2019, the scheme has since been adopted by 17 countries worldwide as it is a simple and cost-effective screening technique.

This study is the largest of its kind and provides the strongest evidence yet that the tools to improve welfare in these popular breeds are already in breeders’ hands. It was conducted using the Kennel Club and the University of Cambridge Scheme and analysed data from more than 4,000 dogs assessed through the RFGS, a standardised respiratory function test. By looking at the results of the progeny, researchers were able to estimate how much of the variation in breathing ability between dogs can be attributed to genetics. The answer, for all three breeds, was a moderate but meaningful proportion: heritability estimates ranged from 0.21 to 0.49, a level comparable to many traits already successfully selected for in companion animals.

Put plainly: a pug, French bulldog or bulldog’s risk of breathing problems is not simply a matter of chance or appearance. It runs in families. Breeders who prioritise health-tested dogs are not just doing right by their own litters. Over time, they are also contributing to the long-term improvement of the breed.

“Noisy breathing is never normal,” said Ladlow. “If you can hear a dog struggling to breathe, they are affected. That is what the grading scheme is built on, and it is what this research confirms. We can test these dogs, we can identify the ones that should not be bred from, and we can show that it works.”

“We originated the RFGS here in Cambridge and I am proud to have contributed to this paper, to see it generating the kind of data that proves selective breeding works is exactly what the scheme was designed to do.”

The research also highlights a significant gap. Testing rates remain low across all three breeds, with show-bred dogs far more likely to be assessed than the wider pet population. The majority of dogs being bred in the UK are not being tested at all. Until participation becomes standard practice across all breeding dogs, the scheme’s potential to drive population-level improvement will remain limited.

“Bulldogs are proud to have been part of the research and testing for RFGS. In the show ring the quiet breathing and less stress is testament to it working and improving the dogs being bred. Success depends on the majority of breeders joining in and the more generations tested, the more the hereditary results will make breeding safer and successful,” commented Vicky Collins-Nattrass, Breed Health Coordinator.

Ladlow developed the RFGS alongside Dr Nai-Chieh Liu at the University of Cambridge, validating it against whole-body barometric plethysmography, a specialist breathing assessment available at GVS. She has since trained assessors across the UK and extended the scheme to cover a further 14 brachycephalic breeds, launched at Crufts earlier this year. At GVS, she leads a specialist airway clinic offering assessments, advanced surgery and breeding advice for owners and referring vets.

Today’s findings build on two earlier studies from the same research group. Work published in The Veterinary Journal found that the internal anatomy driving BOAS differs significantly between breeds, with distinct problem areas in pugs, French bulldogs and bulldogs requiring different surgical approaches. A separate study published in PLOS One, found that the Pekingese and Japanese Chin have rates of clinically significant breathing problems comparable to the three most popular breeds. Together, the three studies tell a clear story: BOAS is serious, it is common across a wider range of breeds than most people realise, and it is not inevitable.

“We want owners to stop and think before they buy a flat-faced dog,” said Ladlow. “If you do want one of these breeds, buy from health-tested parents, both dam and sire. If you already have one and suspect they are struggling to breathe, get them assessed early. And if you are breeding, testing is not optional. The puppies you produce should have a long, healthy life ahead of them, and the families who love them should be able to enjoy them for years to come.”

Granta Veterinary Specialists is an independent referral practice based in Cambridgeshire, run by its founding clinicians and staffed by trusted Specialists and their highly-skilled veterinary teams. It exists to provide advanced care for animals that need more than a first opinion practice can offer, and to give the people who love them the answers they deserve.