Why Flat-Faced Dogs Overheat: Frenchies, Pugs & Bulldogs in Summer

If you share your home with a French Bulldog, Pug, or Bulldog, summer needs a little more planning. Flat-faced breeds overheat more easily than other dogs - here's the research on why, which breeds are most at risk, and how to help them stay cool.

The short answer: Flat-faced (brachycephalic) dogs are about twice as likely to suffer heatstroke as other breeds, because their shortened airways make panting - a dog's main cooling system - far less effective. A large UK study of over 900,000 dogs found Bulldogs were 14 times more likely and French Bulldogs 6 times more likely to develop heatstroke than Labradors. The fix is prevention: avoid midday heat, keep them cool and hydrated, and know the warning signs.

Why flat-faced dogs overheat so easily

Dogs don't sweat like we do - they shed heat mainly by panting, moving air across the wet surfaces of the mouth and airway. Brachycephalic breeds have the same amount of soft tissue packed into a much shorter muzzle, so their airways are crowded and panting moves less air. Researchers put it bluntly: a flat-faced dog can generate more heat gasping to breathe than it loses by panting. That's why a warm day that a Labrador shrugs off can put a Frenchie in trouble.

The breeds most at risk

The Royal Veterinary College study of more than 900,000 UK dogs ranked heatstroke risk against Labrador Retrievers. The highest-risk breeds included:

  • Chow Chow - 17x more likely
  • Bulldog - 14x more likely
  • French Bulldog - 6x more likely
  • Dogue de Bordeaux - 5x more likely
  • Greyhound - 4x more likely
  • Pug and Cavalier King Charles Spaniel - about 3x more likely

Heatstroke is not a minor event: the same research found that roughly one in seven dogs treated for heatstroke died from it. Prevention is the whole game.

Other things that raise the risk

Body shape isn't the only factor. The study found dogs that were overweight, and dogs over two years old, were at higher risk - and dogs that were large for their breed had about one and a half times the risk of smaller ones. If your flat-faced dog is also carrying extra weight, summer caution matters even more.

How to help a flat-faced dog stay cool

Keep walks to the cool ends of the day and skip them entirely in a heatwave. Never leave your dog in a parked car. Make sure water is always within reach, keep air moving with a fan, and draw the blinds on the sunny side of the house. A cool surface to lie on helps too - a cooling mat gives a hot Frenchie or Pug a spot to settle instead of sprawling on bare tile. Think of it as one part of a cool-and-calm setup, alongside shade, water, and avoiding the heat of the day.

Know the warning signs

Because flat-faced dogs have so little margin, act early. Frantic or noisy panting, drooling, bright red or bluish gums, wobbliness, vomiting, or collapse can signal heatstroke - a true emergency. Move your dog somewhere cool, offer water, and get to your vet or an emergency clinic immediately. With brachycephalic breeds, sooner is always better.

Frequently asked

Why do French Bulldogs and Pugs overheat so easily? Their shortened airways make panting - a dog's main way to cool down - far less effective, so they struggle to shed heat. Research found flat-faced breeds are about twice as likely to suffer heatstroke, with Bulldogs 14 times and French Bulldogs 6 times more likely than Labradors.

What temperature is dangerous for a flat-faced dog? There's no single number, but brachycephalic dogs can struggle in weather other dogs tolerate. Be cautious well before it feels hot to you, avoid midday walks, and watch for heavy panting or distress rather than relying on the thermometer alone.

How can I keep my Frenchie or Pug cool in summer? Walk in the cool hours, never leave them in a car, keep water and airflow available, and give them a cool spot to lie on. Learn the signs of heatstroke and act fast - with flat-faced breeds, early action matters most.

Sources: Royal Veterinary College and Nottingham Trent University VetCompass study of 900,000+ UK dogs (2020); reporting via BBC Science Focus and The Conversation. General information, not veterinary advice - for concerns about your dog, contact your vet.

Keep reading from The Pet Den

See the Coolden cooling mat - gel-free, cool on contact, backed by the Pet Den Promise.

Back to blog