French bulldogs struggle to breathe year-round. Extreme heat is making it worse.

Earlier this year, the French bulldog — or the “Frenchie,” as the breed is affectionately known — was named the United States’ most popular dog, ending the Labrador’s 31-year reign. But some of the characteristics that make the Frenchie so irresistibly cute — the scrunched-up flat face, the little button nose, the giant tongue — can also make it hard for them to breathe, especially during the record-breaking heat waves gripping much of the US and the world this summer.

Frenchies, along with English bulldogs (ranked 6th) and pugs (ranked 35th), and around 20 other flat-faced breeds, are brachycephalic, meaning they have unusually short skulls. This makes the soft palate at the back of their mouths too long for their heads, which blocks airflow into the windpipe and lungs. Some of the traits that make it harder for them to breathe are obvious to the naked eye, like their narrow nostrils and large tongues.

Taken together, these conditions make them highly susceptible to brachycephalic obstructive airway syndrome, or BOAS, which veterinarians say is a chronic, lifelong, debilitating respiratory disease that degrades their quality of life. Brachycephalic breeds also have shorter lifespans; in the United Kingdom, French bulldogs have the lowest life expectancy of all breeds, at an astonishingly short 4.5 years. One University of Cambridge study found that 90 percent of Frenchies tested had some level of airway restriction.

Some owners put their dogs through invasive surgeries, like widening their nostrils, just to give them some relief.

“Imagine breathing with somebody holding your nose … and your throat’s really swollen,” said bioethicist Jessica Pierce, drawing from an article in DogTime. “Imagine breathing like that all the time.”

It’s estimated that around half of Frenchies, pugs, and English bulldogs suffer from BOAS, though many may not get the veterinary care they need as most owners see the clinical signs of BOAS — snorting, snoring, and heavy breathing — as normal.

“You’ll have people say that the snuffling sound is so cute, and it’s actually a dog struggling to breathe,” said Pierce, who has authored books on animal behavior and welfare, most recently Who’s a Good Dog? “I think it’s just a lack of empathy, and a lack of awareness.”

Just like for humans with respiratory issues, extreme heat makes it all the worse: Brachycephalic dogs are much more likely to suffer heat-related illness events than other breeds.

Emma Goodman Milne, a veterinarian in France, said that unless you live in an especially cool climate, there are “vast swathes of the day that [brachycephalic dogs are] incapable of exercising comfortably because a) they can’t breathe, and b) they can’t heat-regulate either. So they’re much more prone to heat exhaustion and heatstroke, and I think people often underestimate that.”

Milne said that while individual dogs vary, brachycephalic breeds tend to begin panting at much lower temperatures than other dogs — a difference of around 20 degrees Fahrenheit. Given that temperatures are expected to rise in the years ahead, we may want to add one more task to humanity’s climate change adaptation to-do list: Stop breeding dogs that struggle so much in the heat.

“It’s just a low-hanging fruit if you want to reduce dog suffering,” said Pierce.

How to keep your dog cool on a warming planet

There’s a lot we can do for brachycephalic breeds — and all dogs — to keep them cool as summers get hotter (and smokier).

The most obvious and effective thing to prevent heat exhaustion and heatstroke is to avoid the heat. This summer, I’ve taken to walking my dog, Evvie, in the mornings and evenings (while keeping daytime walks under 10 minutes). I try to not get too far from home in case she starts to display signs of overheating: According to the ASPCA, those include excessive panting, difficulty breathing, increased heart rate, drooling, mild weakness, or collapse. More severe symptoms can include “seizures, bloody diarrhea, and vomit along with a body temperature of over 104 degrees.”

If you haven’t already, identify your closest 24/7 emergency veterinarian office in the event your dog’s health goes downhill fast in extreme temperatures. And if your dog is really hot, be mindful to not cool them down too rapidly or too much, which can cause a condition called rebound hypothermia.

For the sake of my dog’s health and happiness, I abandon all sense of fashion on these walks and wear a decked-out fanny pack big enough to store a little water bowl and bottle of water if it’s particularly hot and sunny. Pierce’s daughter puts a cooling vest on her dog Poppy.

Poppy the dog wearing a cooling vest.
Sage Madden

Beyond the air temperature, there’s asphalt, which can get exceptionally hot and cause injury to dogs.

“A good rule of thumb is to place a hand on the surface of the pavement for 10 seconds. If the pavement is too hot for your hand, then it’s too hot for your pets’ paws,” said Lori Bierbrier, senior medical director for ASPCA Community Medicine, in an email to Vox. And since dogs’ bellies are so low to the ground, heat rising from the asphalt affects them more than it does us. When possible, walk on grass and dirt. (Disclosure: This summer I attended a media fellowship program at Vermont Law and Graduate School that was funded by the ASPCA.)

When it’s very hot, keep outdoor time to a minimum, especially for the dogs most at risk of heat exhaustion. In addition to brachycephalic breeds, that group includes dogs who are overweight, senior dogs, puppies, and those with lung and heart conditions.

Amid their humans’ busy schedules, dogs may already be quite bored. With fewer opportunities for walks and exercise, they could become even more frustrated during the hot summer months, so be sure to play with them indoors. If possible, arrange doggy play dates (a few times a week, I get my dog together with a neighbor’s).

Evvie, the author’s dog, and her friend Sorin, take a break to beg for treats while playing indoors.
Courtesy of Lynn Rose

Brachycephalic breeds, which struggle to exercise because of their respiratory issues and heat intolerance, could be extra bored.

“Their level of frustration is very high,” Milne said. “You’ll often hear people say that brachycephalics are good pets because they don’t need much exercise.” But they do — they’re just not in good enough shape to be very active, she said. University of Cambridge researchers consider dogs with BOAS to have “exercise intolerance.”

And of course, never, ever leave your dog alone in a parked car. “The temperature inside your parked car may be as much as 20 degrees hotter than the temperature outside,” Bierbrier said. “Not only can it lead to a fatal heat stroke, it’s illegal in many states.”

Fourteen states have “Good Samaritan” laws that allow you to legally break into a parked car with an animal inside if you have a good-faith, reasonable belief that their health or life is at imminent risk. In most of these states, you must first contact law enforcement; familiarize yourself with the laws in your state ahead of time in case you come across a suffering animal in a car.