Also known as brachycephalic dogs, these breeds have increased in popularity in recent years, with celebrities including Reese Witherspoon and David Beckham leading the trend.
However, the researchers said the rising demand for these dogs is concerning, particularly as climate change increases the severity and frequency of heatwaves.
They believe increasing numbers of these breeds, combined with rising UK temperatures, could lead to even more dogs suffering from the potentially fatal condition in the future.
Based on their findings, published in the journal Scientific Reports, the scientists said vets should weigh up the potential risk of heatstroke when advising owners on breed selection.
Emily Hall, lead researcher and a veterinary surgeon at Nottingham Trent University’s School of Animal, Rural and Environmental Sciences, said: “It’s likely that brachycephalic dogs overheat due to their intrinsically ineffective cooling mechanisms.
“Dogs pant to cool down. Without a nose, panting is simply less effective. In fact, brachycephalic dogs may even generate more heat simply gasping to breathe than they lose by panting.”
Researchers at Nottingham Trent University and the Royal Veterinary College analysed anonymised electronic records of more than 900,000 dogs across the UK in what is thought to be the largest study of its kind.
They identified nearly 400 confirmed cases of heat-related illnesses among dogs under veterinary care, but believe actual numbers may be higher because many affected with heatstroke may not be taken to the vet.
The scientists used the labrador retriever, a popular breed in the UK, as the “base” comparison breed to identify dogs at most risk from heat-related illnesses.
They found bulldogs were 14 times more likely to develop heatstroke than labs. French bulldogs were found to be six times more likely and pugs were twice as likely to develop the condition.
In general, flat-faced dogs were twice as likely to suffer with heatstroke, the researchers said.
Other dogs at most risk also include the chow chow, dogue de Bordeaux, greyhound, Cavalier King Charles spaniel, golden retriever and springer spaniel.
Being above average weight and being over two years old were also some of the factors identified by the researchers as predictors for heatstrokes.