Heatstroke in Dogs: Spotting It Early and What to Do

Heatstroke is one of the most dangerous summer emergencies a dog can face, and it can come on frighteningly fast. The good news is that it’s largely preventable, and when you do spot it, a few quick, calm actions - done exactly the right way - can make all the difference to your dog’s recovery.

Here’s what the veterinary charities PDSA and the RSPCA say every UK dog owner should know.

Heatstroke is a veterinary emergency

First, it’s important to be clear about how serious this is. PDSA describes heatstroke as “a very serious condition that can progress very quickly”, and in severe cases it can cause seizures, organ damage and death. Its first-aid page is blunter still: heatstroke is a “life-threatening emergency”. The RSPCA agrees, warning that heatstroke “can be fatal”, so you need to act fast.

A dog’s normal body temperature is around 38-39°C. PDSA explains that once a dog’s temperature rises above 40°C (104°F), they are at risk of heatstroke, which can lead to seizures, organ damage, internal bleeding, coma and even death. The longer it lasts, the more dangerous it becomes - so the quicker your dog is cooled down and seen by a vet, the better their chance of full recovery.

Dogs cool themselves mainly by panting and using shade, because they have a limited ability to sweat. That’s why heatstroke often strikes during play - PDSA notes that nearly three quarters of heatstroke cases develop while a dog is playing or exercising.

Early signs of heatstroke

Spotting the signs early is key. PDSA groups them by severity:

• Mild: panting, fast breathing or difficulty breathing, and lethargy (low energy).
• Moderate: drooling, foaming at the mouth, vomiting, diarrhoea, bright red or very pale gums, shaking, and weakness or collapse.
• Severe: confusion, seizures, unconsciousness, and vomiting or diarrhoea with blood in it.

The RSPCA lists similar symptoms - panting, red gums and tongue, drooling, weakness and lethargy, collapse, confusion, increased heart rate, and seizures - and adds one useful note: vomiting or diarrhoea that contains blood is a sign the heatstroke has become more severe.

If your dog is showing any signs of heatstroke, don’t wait to see if they pass. Start cooling them immediately.

What to do right now: first aid

The RSPCA sums up the priority in three words: “Cool first, transport second.” Getting the dog’s temperature down matters more than rushing anywhere, so here is the exact order both charities recommend.

1. Stop the heating. Stop exercise or movement immediately. Get your dog out of the sun and hot surroundings and into the shade, or better, a cool room indoors (PDSA).

2. Cool them down, correctly. PDSA’s guidance:

• Gently pour cold water over their whole body - “water from the cold tap is fine”. Start slowly so they don’t panic, but soak the whole body as calmly and quickly as you can. The RSPCA suggests focusing on the neck, stomach and thighs, and avoiding their head.
• Keep water away from their nose and mouth so they don’t inhale it - this is especially important if the dog is unconscious.
• If your dog is used to water and won’t panic, you can gently submerge their body (except the head) in cool water, like a paddling pool (RSPCA suggests a stream or paddling pool, as long as the water is cooler than the dog).
• Create a breeze by opening doors and windows or switching on a fan.
• Offer a drink of cold water, but never force them to drink.
• Place the dog on top of a cold, wet towel, or wrap an ice pack (or frozen veg) in a towel and put it between their thighs.

Do not cover or wrap a damp towel over their body. Both PDSA and the RSPCA are adamant about this one: covering a hot dog with a wet towel traps the heat and makes them hotter. Wet towels go underneath the dog, not over them.

It’s also worth knowing the source of the old worry about cold water: the RSPCA explicitly notes that, contrary to popular belief, cold water rarely causes shock in over-heating dogs, and that dousing or immersing the overheated dog in cold water is vital to their recovery. So don’t be squeamish about the cold water - but do go gently so your dog doesn’t panic.

3. Call your vet as soon as possible. Ideally take your dog straight to your nearest vet. RSPCA advises calling ahead to tell them it’s urgent. If you can, keep cooling your dog on the journey - travel in an air-conditioned car or one with the windows open, and bring someone along to keep pouring water while you drive.

Never leave your dog in a hot car

Dogs can be trapped somewhere hot - a car, conservatory or unventilated room - and overheat quickly. PDSA’s rule is absolute: never leave your dog in a car on a warm day, “not even for a few minutes, with the windows open, or in the shade.”

If you see a dog in a hot car showing signs of heatstroke, the RSPCA says to dial 999 immediately and stay with the dog until help arrives.

How to prevent heatstroke

Prevention is far better than treatment. PDSA’s everyday summer tips are:

• Walk when it’s cool - take your dog out in the early morning or evening, and avoid the hottest part of the day. Avoid strenuous exercise on hot days altogether if your dog is unfit, elderly, young, overweight, unwell or has breathing problems.
• Always provide shade and water - and take water with you on walks, especially on warm days.
• Get them wet on warm days - pour water over your dog or let them paddle in cool water, but keep them in the shade and don’t let them get too excited.
• Use a harness instead of a collar while you walk, so less pressure is put on their throat and it’s easier for them to pant - this matters most for brachycephalic (flat-faced) dogs.
• Never walk on hot surfaces - if you can’t comfortably hold the palm of your hand on the ground for seven seconds, it’s too hot. Sand, artificial grass and tarmac get especially hot.

Both charities agree some dogs are far more at risk: flat-faced breeds (such as Pugs, English and French Bulldogs), overweight, elderly, very young, giant-breed, and thick-coated dogs. PDSA adds a striking statistic: British Bulldogs are 14 times more likely to develop heatstroke than Labradors, and Pugs 6 times more likely. If you own one of these dogs, take extra care even on cooler days.

If you think your dog has heatstroke, start cooling them immediately and call your vet right away - don’t wait to see if they improve.

Sources

• PDSA - “Heatstroke in Dogs”: https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/conditions/heatstroke-in-dogs
• PDSA - “First Aid for Heatstroke”: https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/other-veterinary-advice/first-aid-for-heatstroke
• RSPCA - “How to Recognise & Treat Heatstroke in Dogs”: https://www.rspca.org.uk/adviceandwelfare/pets/dogs/health/heatstroke

This article is for general information and is not a substitute for professional veterinary advice. If your pet is unwell or you’re concerned about heatstroke, contact your vet immediately or call the RSPCA cruelty line.