What to Do With a Dog During a Heatwave: Prevention, Warning Signs, and First Aid

A heatwave puts real strain on a dog, and heatstroke can go from "he's just panting a lot" to a life-threatening emergency in a short space of time. Dogs cannot sweat their way out of trouble the way we do: they shed heat mainly by panting, and panting works poorly in hot, humid, still air. This guide is for anyone whose dog is facing a hot spell. It covers how to keep your dog cool, the earliest signs that something is going wrong, what to do in the first few minutes, and when to get to a vet.

Why are dogs so vulnerable to heat?

Dogs lack the extensive sweat glands people have, so they rely on evaporating water from the moist surfaces of the airways. To shift more heat they have to move more air, which is active work that generates heat of its own. In flat-faced breeds, narrowed airways make that work harder still, so each breath costs more effort and produces more heat. That same research found something owners often miss: body condition was an even stronger predictor of body temperature than skull shape. An overweight dog of any breed is at a disadvantage in the heat.

A normal rectal temperature in a dog is around 38.6 to 38.9 °C. Once core temperature climbs to roughly 41 °C and above, vets treat that as a critical level, particularly when the dog is also confused, wobbly or collapsed. A thermometer reading on its own does not tell the whole story, though. Fit dogs can briefly exceed that after exercise without becoming ill, and a dog who has already been cooled may read normal while still being in trouble. Treat the clinical signs as the priority.

It also does not need to be a spectacular heatwave. Among UK dogs treated for heat-related illness, the median outdoor temperature on the day of the event was only 16.9 °C. Hot days simply make everything worse and faster.

Which dogs are most at risk

• Flat-faced (brachycephalic) breeds: Bulldogs, French Bulldogs, Pugs and similar breeds. Bulldogs, French Bulldogs and Chow Chows came out among the highest-risk breeds in a large study of UK primary care records, along with dogs carrying more weight than average for their breed, dogs over two years old and dogs weighing more than 50 kg.
• Older dogs: age comes up repeatedly as a risk factor, partly because older animals are more likely to have heart or airway disease.
• Overweight dogs and unfit dogs: less efficient at losing heat, quicker to overheat.
• Thick-coated dogs and dogs with heart or breathing conditions
• Dogs not used to the heat: heat acclimatisation takes weeks of gradual exposure, so the first hot days after a cool spell are among the most dangerous of the year.

Enthusiastic retrievers, spaniels and working breeds are not exempt either. They are over-represented in exercise-triggered cases precisely because they keep going when they should stop.

How do I keep my dog cool in a heatwave?

Most heat emergencies are preventable, and the biggest single change you can make is to stop exercising your dog in the heat. The Royal Veterinary College's work on heat-related illness found that almost three quarters of cases followed some form of activity, and ordinary walking alone accounted for around two thirds. Hot cars get the headlines, but they made up a much smaller share of cases.

Time walks around the heat, or skip them

Walk early in the morning and late in the evening. On a genuinely hot day, a short toilet break in the shade is enough. Your dog will cope fine with a missed walk. They may not cope with a hot one.

Swap the exercise for something indoors: a game of fetch down a hallway, a dog-safe obstacle course, scent games, or swimming if you have safe access to water. Indoor and water-based activities burn energy without the heat load.

Check the ground before you walk

Surfaces in direct sun run far hotter than the air, by roughly 20 to 33 °C on materials like asphalt, concrete, sand and metal. On a 30 °C day, asphalt can reach around 57 °C, hot enough to burn paw pads within about a minute. Press the back of your hand flat on the ground: if you cannot hold it comfortably for five to seven seconds, it is too hot for paws. Choose grass or shaded dirt paths, or wait.

Signs of burnt pads include limping, refusing to walk, licking or chewing at the feet, and redness, darkening or blisters on the pads. Move your dog off the hot surface, rinse the paws with cool water, skip the ice, and speak to your vet if the pads look blistered or raw.

Never leave your dog in a parked car

Interiors heat up fast. When it is 24 °C outside, a car can reach 38 °C within minutes, and opening a window is not a fix. There is no safe version of this in hot weather. If your dog cannot come inside with you, leave them at home.

If you must travel, go at cooler times, keep the car ventilated or air-conditioned, plan shaded stops, and avoid getting stuck in traffic with a dog in the back.

Shade, water and moving air at home

• Make sure the shade is deep and stays shady as the sun moves, not a patch that disappears by midday.
• Keep several bowls of fresh water available and offer small amounts regularly when you are out. Let a heavily panting dog settle before gulping large volumes, which can bring on bloating and vomiting.
• Keep air moving with a fan or air conditioning, and close blinds on the sunny side of the house.
• A cooling mat, a shallow paddling pool or a damp cool surface to lie on all help.
• Regular grooming and a tangle-free coat make it easier for your dog to regulate their own temperature. Pale dogs and exposed skin on ear tips and noses can burn, so ask your vet about a pet-safe sunscreen.
• Do not use anything that stops a dog panting freely, and never muzzle a flat-faced dog or leave a muzzled dog unattended.

If there is a cat in the household as well, they need their own hot weather plan, since cats show overheating differently.

What are the warning signs of heatstroke in a dog?

Heat-related illness is progressive. It moves through stages, and the earlier you intervene the better the outlook. Dogs treated while still mild or moderate survive at around 95 percent, compared with roughly 43 percent of those who arrive already severe.

Early signs, where you should stop everything and start cooling:

• Heavy or continuous panting that does not settle after activity stops
• Lethargy, drowsiness, stiffness or reluctance to move
• Excessive drooling, sometimes thick and sticky
• Shade seeking, restlessness or agitation
• Bright pink or red gums and lips, hot skin, racing heart
• Looking wobbly or uncoordinated

Emergency signs, where you cool and head straight for a vet:

• Difficulty breathing or a clear change in breathing effort
• Vomiting or diarrhoea, especially with blood
• Confusion, disorientation, a blank stare, stumbling
• Collapse, seizures or loss of consciousness
• Bruising, bleeding, or pale or blue-tinged gums
• A measured temperature of about 41 °C or higher

Flat-faced dogs can deteriorate very quickly. With them, breathing changes in warm weather are enough on their own to justify a call.

What do I do if my dog is overheating?

The rule vets and welfare organisations agree on is: cool first, transport second. Cooling started at the scene, and continued in the car, gives your dog a better chance than driving straight there without it.

1. Stop and get out of the heat: end the walk or game immediately, move into shade or indoors, and get air moving over your dog with a fan or breeze.
2. Start pouring water over the body straight away: use whatever water is available as long as it is cooler than your dog. Douse the body and legs continuously, and keep water away from the face and head. Wet fur plus moving air cools much faster than either alone.
3. Know that immersion advice varies: some organisations now recommend immersing a young, healthy, fully conscious dog in cold water while keeping the head above the surface, while others still advise against putting a dog in a tub. If you are unsure, or your dog is old, unwell or not fully alert, stick with continuous dousing plus a fan and phone your vet for direction.
4. Do not leave a wet towel draped over your dog: a towel left in place can trap heat. If you are using towels, place them around the neck, armpits and groin and swap them for freshly wetted ones every few minutes.
5. Offer small amounts of cool water to drink: only if your dog is fully conscious and swallowing normally. Never pour water into the mouth of a drowsy, vomiting or collapsed dog.
6. Call the vet or emergency clinic while you cool: tell them you suspect heatstroke so they can prepare, and keep the car cool and ventilated on the way.
7. Stop active cooling at around 39.2 to 39.4 °C: if you can check a rectal temperature, stop cooling once it reaches that range so your dog does not swing too far the other way. Stop too if your dog starts shivering.

Even a dog who seems fine again needs to be seen. Kidney injury is present in essentially all dogs with heatstroke and is often silent at first, and clotting problems can develop over the hours that follow. Outward recovery is not the same as being out of danger.

When should I call the vet?

Contact a vet or emergency clinic straight away if your dog shows any of the following:

• Collapse, seizures or loss of consciousness
• Any difficulty breathing, and especially in a flat-faced breed
• Persistent vomiting or diarrhoea, particularly with blood
• Bright red, pale or blue-tinged gums
• Stumbling, disorientation or a temperature around 41 °C or higher
• Heavy panting that does not settle within a few minutes of stopping and cooling

Out-of-hours arrangements differ from country to country and from clinic to clinic, so find out now how your practice handles emergencies and save both that number and the nearest emergency clinic before the hot weather arrives. If you are unsure whether what you are seeing counts, call anyway. Vets far prefer an early phone call to a late arrival.

The takeaway

Heatstroke in dogs is common, fast-moving and largely preventable. Move walks to the cool hours or skip them, test the ground with the back of your hand, keep shade and water available, and never leave your dog in a parked car. Learn what early heat stress looks like, because a lethargic, heavily panting dog on a hot day is already telling you something. If your dog does overheat, start pouring cool water over them before you do anything else, phone ahead, and keep cooling on the way. Getting there early is what changes the outcome.

This guide is general information and does not replace veterinary advice. If you are worried about your dog, contact your vet.