Heat Stress in Dogs: Recognising the Symptoms and Preventing Overheating

Heat stress in dogs shows up as panting, drooling and lethargy. Learn the symptoms, first aid steps and tips to prevent overheating this summer.

On a warm summer's day, a dog can overheat within half an hour — especially during a brisk walk or in a car that heats up quickly. Heat stress happens when a dog can no longer regulate its body temperature in time. Early signs include excessive panting, drooling and lethargy; if the heat exposure continues, this can escalate into heatstroke, an acute emergency. Below, you'll find out how to recognise the symptoms, what to do straight away, and — most importantly — how to prevent it.

What is heat stress in dogs?

Dogs cool themselves mainly by panting, and to a lesser extent through sweat glands in their paw pads. This is far less effective than the way humans sweat. In high temperatures, high humidity or during exercise, the body can't release heat quickly enough, causing body temperature to rise. If this continues, it's known as heat stress; in the worst cases, it can lead to heatstroke, which can cause organ damage.

Symptoms: what to look out for

The first signs are often subtle, which makes them easy to miss:

• Excessive, rapid panting, even at rest
• Heavy drooling
• Lethargy or unusually quiet behaviour
• Red gums or a bright red tongue
• Reluctance to walk, or lagging behind during walks

If it worsens, more serious symptoms can appear: vomiting, diarrhoea, staggering, confusion, or even collapse. These are signs of heatstroke.

Which dogs are most at risk?

Any dog can suffer from heat stress, but some are more vulnerable than others:

• Short-nosed (brachycephalic) breeds such as the French Bulldog, Pug and Boxer — their breathing is already less efficient
• Overweight dogs
• Senior dogs and puppies, who regulate their temperature less effectively
• Dogs with a thick or dark coat
• Dogs with a heart or respiratory condition

At what temperature does walking or cycling become too risky?

There's no hard cut-off point — the risk depends on humidity, sun exposure and your dog's fitness. Even so, vets and animal welfare organisations use a number of rules of thumb that make a useful guideline:

• From around 20°C: be extra alert, especially with flat-faced (brachycephalic) breeds, overweight dogs or those with a thick coat. A normal walk is still fine, but build in rest breaks in the shade.
• From around 25°C: avoid exercise between roughly 11am and 4pm, when the sun is at its strongest. Move the walk to early morning or late evening instead.
• Above 30°C: stick to short, essential toilet breaks in the shade. Cycling or running with your dog is not advisable at this point.

Cycling is more strenuous for a dog than walking: he often has to keep up a pace faster than his natural trotting speed, which makes his body temperature rise more quickly. If in doubt, apply a lower temperature threshold for bike rides than for a gentle walk. Always combine the temperature with the tarmac test mentioned earlier: even at a moderate temperature, the sun can have heated the road surface considerably, increasing the risk of heat stress or heatstroke.

What to do if your dog overheats

Act calmly but quickly:

• Move your dog into the shade or a cool space straight away
• Let them drink water calmly — don't force it
• Wet their coat and paws with cool (not ice-cold) water; ice-cold water constricts the blood vessels and can be counterproductive
• Turn on a fan or make sure there's good air circulation
• If in doubt, always contact a vet, especially if you notice any of the serious symptoms mentioned above

A damp towel is worth its weight in gold at this point: lay it over the neck, armpits and groin, where large blood vessels run close to the skin. A reusable pet towel is handy for this, as it holds plenty of moisture and can be used again and again for exactly this purpose.

Preventing heat stress: practical tips

When it comes to heat stress, prevention is always better than cure — and it's usually simple, too.

For longer summer walks, it's worth planning a route with plenty of shade in advance. It's also worth thinking ahead about the right gear to help keep your dog comfortable along the way.

Frequently asked questions

Can a dog survive heat stress?

Yes, provided action is taken quickly. The sooner a dog is cooled down, and the sooner a vet is consulted in the case of serious symptoms, the greater the chance of a full recovery.

Should I shave my dog in summer?

For most breeds, this isn't recommended: a dog's coat actually protects against sunburn and insulates against heat. If you're unsure, ask a groomer or vet what's best for your dog's coat type.

Can my dog overheat indoors too?

Yes. A poorly ventilated room, a car parked in the sun, or a garden without shade can all lead to heat stress, even if your dog hasn't been active.

Is pouring water over my dog's head good first aid?

It's better to wet the neck, armpits and groin with cool water and let your dog drink calmly. Avoid ice-cold water, as this can actually slow down the cooling process.

In short

Heat stress in dogs often starts unnoticed — excessive panting, drooling and lethargy — but it can quickly escalate into an emergency. Know your dog's individual risk factors, adjust walking times to the temperature, always provide water and shade, and never leave your dog alone in the car. If you're ever unsure about your dog's condition, always contact your vet.

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