The human-canine alliance has gone from strength to strength since our ancient ancestors first began feeding scraps to wild wolves, although this sacred interspecies bond has also produced some unfortunate consequences. The creation of designer dog breeds featuring shortened snouts, for example, has left many pooches suffering from ill health, and a new study reveals that these breeds are also much more likely to suffer from heatstroke than longer-nosed dogs.
Publishing their work in the journal Scientific Reports, the study authors analyzed the clinical records of more than 900,000 pet dogs under veterinary care in the UK in 2016, and identified 1,222 cases of heat-related illness. A closer look at the data revealed that dog breeds with a brachycephalic skull – which is characterized by a shortened head, flat face, and short nose – were generally the most likely to be afflicted by heat.
Among the nine breeds that were found to be most at risk of suffering heatstroke, five have a brachycephalic skull. Bulldogs, for instance, were found to be 14 times more likely to require veterinary care for heatstroke than Labrador retrievers, while French bulldogs were six times more likely and pugs were three times as susceptible to the condition.
In a statement, study author Emily Hall explained 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,” she said.
Yet it isn’t just short-faced dogs that struggle with heat, as they found chow chows to be at more risk than any other breed. Seventeen times more likely to suffer heatstroke than Labrador retrievers, chow chows have a thick double coat that traps warm close to their skin. While this is great for staying warm in cold climates, it makes it very difficult to cool down on a hot day.
Body size was also found to be a risk factor, with dogs that are above the average weight for their breed being 1.5 times as likely to suffer heatstroke as those that are small for their breed. Furthermore, dogs weighing more than 50 kilograms (110 pounds) were almost 3.5 times more at risk than dogs weighing under 10 kilograms (22 pounds).
In fact, small lap dogs with a bodyweight of under 10 kilograms seem to be the most immune to the effects of heat, as their high heat storage to radiative surface area ratio means they cool down much faster than bigger animals.
Of all the dogs in this study that had been treated for heatstroke, 14.18 percent died, indicating just how important it is to help pets stay cool. If left alone in a car on a hot day without any water, a dog can overheat and die in as little as 20 minutes, so it’s essential to take care of your dog when the mercury rises.