Heatstroke in Pets — Emergency Signs and Action Guide

Why Dogs and Cats Are Vulnerable to Heatstroke

Unlike humans, dogs and cats cannot sweat through their skin to cool down efficiently. Dogs cool primarily by panting — rapidly moving air across the moist surface of the mouth, tongue, and airways — and cats do the same, though they also groom their fur to allow evaporative cooling from saliva. Both mechanisms are significantly less efficient than sweating across a large skin surface area.

Brachycephalic (flat-faced) breeds — French Bulldogs, English Bulldogs, Pugs, Persian cats, and others — are at dramatically higher risk because their narrowed airways make panting less efficient. Overweight animals, elderly animals, and those with underlying respiratory or cardiovascular conditions are also at elevated risk. Even fit, healthy dogs can develop heatstroke rapidly during vigorous exercise in warm, humid conditions.

Signs of Heatstroke in Dogs

Early signs of overheating include: heavy, laboured panting; seeking shade or lying flat on cool surfaces; reluctance to continue activity; increased thirst and salivation; glassy or dull eyes.

Signs of established heatstroke — which require immediate emergency response: extremely rapid, loud, distressed panting; vomiting or diarrhoea (sometimes bloody); extreme lethargy or weakness; staggering, stumbling, or inability to stand; bright red gum colour, followed by pale, grey, or blue-tinged gums as shock develops; raised core temperature (above 39.5°C is elevated; above 41°C is dangerous; above 43°C is critical); seizures; and loss of consciousness.

Once a dog has begun showing the more serious signs, every minute without active cooling and veterinary care worsens the prognosis.

Emergency Cooling — What to Do Right Now

If your dog shows signs of heatstroke, begin cooling immediately while someone else calls the vet or while driving to the emergency vet: 1. Move your dog to shade or a cool indoor environment immediately. 2. Apply cool (not ice cold) water over the body — particularly the neck, armpits, and groin. Cool wet towels draped over the body and changed regularly work well. Avoid ice, ice water, or ice packs — these cause peripheral vasoconstriction and can trap heat inside the body, worsening the situation. 3. Allow your dog to drink cool water if they are conscious and able to swallow, but do not force it. 4. Fan the dog while applying cool water. 5. Drive to the vet immediately — do not wait for your dog to look better before going.

Do not use cold water baths or ice-water immersion; they can cause dangerous shock. The goal is gradual cooling, not the fastest possible temperature reduction.

Common Causes of Heatstroke in UK Pets

Hot cars are the single most common cause of fatal heatstroke in UK dogs. On a 22°C day, the interior of a parked car can reach 47°C within 60 minutes — cracking a window makes little difference. Never leave a dog in a car in warm weather, even for 'just a few minutes'. The British Veterinary Association recommends calling 999 if you see a dog in a hot car in visible distress.

Other common causes include: exercising dogs in the hottest part of the day (walk early morning and evening in summer); leaving dogs in garden without shade or water; leaving dogs in conservatories or glass extensions; dog sitting in direct sun during outdoor events; and hot tarmac causing paw burns and radiated heat contributing to overheating.

Prevention Tips for Hot Weather

Walk dogs early morning (before 9am) and late evening (after 7pm) during heat waves. Always carry fresh water for your dog. Provide shade and cool water in the garden. Never leave any pet in a car during warm weather. Use a paddling pool or damp towels for brachycephalic breeds on warm days. Avoid pavement and tarmac in the hottest part of the day — if the pavement is too hot to hold your own hand flat against it for 5 seconds, it is too hot for your dog's paws. Consider a cooling mat or damp towel for dogs to lie on. Groom double-coated dogs appropriately (do not shave double coats — the outer coat can provide some insulation).