Heat and Your Dog on Holiday: How Hot Is Too Hot

Heat is the biggest danger most dogs will ever face on a holiday, and it catches out careful, loving owners every summer. It does so because nearly everyone has the wrong picture in their head. We have all been taught that dogs die in hot cars. They do. But the research says that is not where most of the harm is done, and a holiday is exactly when the real risk goes up: you are somewhere warmer than home, you are outdoors all day, and you want to do things. This guide explains where the danger really lies, how to judge the heat for your own dog, how to plan a hot day so that everyone enjoys it, and what to do if your dog overheats.

It Is the Walk, Not Just the Car

In 2020 researchers at the Royal Veterinary College and Nottingham Trent University looked at the veterinary records of more than 900,000 dogs in Britain. Their finding surprised a lot of people. Exercise was responsible for 74% of heatstroke cases. Hot weather alone, with the dog simply sitting outside, accounted for 13%, and hot cars accounted for 5%.

Two details in that study matter for anyone on holiday. Of the cases triggered by exercise, 68% happened after nothing more strenuous than a walk. And about one dog in seven that was treated for heatstroke died of it. The lead researcher, Emily Hall, put it plainly: "dogs don't just die in hot cars. Taking a dog for a walk or a run in hot weather can be just as deadly so consider skipping walks altogether during heatwaves". That is the single most useful thing to take away. A dog will not come to harm from missing a walk, and it can come to serious harm from having one.

Which Dogs Are Most at Risk

Any dog can overheat, but some are in much more danger than others. Dogs cool themselves almost entirely by panting, so anything that makes panting less effective raises the risk. Flat faced breeds, such as bulldogs, French bulldogs and pugs, are the most vulnerable of all. The same study found that they were at increased risk even when sitting quietly outside in hot weather, and particularly at risk in cars.

Older dogs, overweight dogs, dogs with thick or double coats, puppies, and dogs with heart or breathing problems are all more at risk too. The study also found that young, male, energetic dogs were the ones most likely to overheat through exercise, which makes sense, because they are the ones that will not stop. If your dog is in one of these groups, treat every figure in this guide as too generous and act earlier.

How Hot Is Too Hot

There is no single magic number, and anyone who gives you one is guessing, because humidity, sun, breeze, the surface underfoot and your own dog all change the answer. But owners ask us this more than almost anything else in summer, so here is the rule we work to, which is deliberately cautious. Below about 20°C, most healthy dogs are fine for normal exercise. From the low twenties, start being careful, with shorter walks, shade, water, and no ball games.

From about 24°C, we treat it as a day to walk only early and late and to keep it gentle. At 32°C or more, we treat it as too hot to walk any dog, whatever the breed, and the same applies when it feels that hot because of humidity. For a flat faced dog, take about four degrees off every one of those figures. Remember also that the temperature on your phone is measured in the shade. In direct sun, on a south facing beach or a city pavement, it is hotter than the forecast says.

The Ground Under Their Feet

Dogs walk barefoot. Tarmac, paving, sand and artificial grass all get far hotter than the air on a sunny day, and a dog's pads will burn. The test is simple. Put the back of your hand flat on the ground and hold it there for five seconds. If you cannot keep it there comfortably, your dog should not be walking on it. On a hot day, walk on grass and in shade, and carry a small dog across a hot car park or a stretch of beach. In a city, plan your route along the shady side of the street, and remember that a pavement stays hot for some time after the sun has left it.

Planning a Hot Day

The trick on holiday is not to give up doing things but to rearrange the day around the heat, the way people who live in hot countries do. Walk at dawn and again after sunset, and make those the proper walks. In the middle of the day, be somewhere cool: the shade of trees, a room with the shutters closed, a stone floor, a café terrace under an awning.

Choose shaded routes, woods over open hillsides, and a beach in the early morning over the same beach at two in the afternoon. Carry more water than you think you need and a bowl, and offer it often. Let your dog paddle or swim where it is safe. And leave the ball at home. A dog chasing a ball will run itself into heatstroke and never tell you, because the chase matters more to it than how it feels.

When you choose where to stay in summer, ask about the things that keep a dog cool: air conditioning, a cool floor in the room, shade and grass outside, and somewhere to walk first thing in the morning without crossing a baking car park. Our guide to the questions to ask any hotel suggests how to find out. If you have picked a hotel where your dog can stay in the room, a cool room is a far better place for it in the heat of the day than trailing round a hot town with you.

Cars

The car is not the main cause of heatstroke, but it is still deadly, and holidays involve a great deal of driving. The RSPCA warns that when it is 22°C outside, the inside of a car can reach 47°C within an hour. Parking in the shade or leaving a window open does not make it safe.

On a warm day, either someone stays with the dog with the air conditioning running or the dog comes with you. On a long drive, travel early, keep the car cool, check that the air is reaching the back where the dog is, and stop often for water. Our guide to driving with your dog covers long journeys in summer, and the same care applies on a ferry, where a dog left on a car deck cannot be checked during the crossing.

Know the Signs

Heatstroke comes on fast. The early signs, according to the RSPCA, are heavy panting, noisy or laboured breathing, drooling that is thicker than usual, and gums and tongue that are very red. As it gets worse the dog becomes weak, confused or unsteady on its feet, may vomit or have diarrhoea, and can collapse or have a seizure. If your dog is panting hard and will not settle in the shade, treat that as the start of it, and not as normal.

If Your Dog Overheats

What you do in the first few minutes matters more than how fast you get to a vet. The RSPCA's rule is cool first, transport second. Stop the dog moving and get it out of the sun. Pour water over its body, any water that is cooler than the dog, and concentrate on the neck, belly and inner thighs. Keep it off the head, because the dog is already struggling to breathe. If there is a stream, a paddling pool or the sea, and your dog is young, healthy and conscious, put it in. Fan it, or put it in a breeze. Offer water to drink but do not force it.

Two pieces of old advice are wrong and worth unlearning. Do not drape wet towels over the dog, because they trap the heat, though a wet towel underneath is fine. And do not worry that cold water will send the dog into shock. The RSPCA is clear that this rarely happens and that dousing or immersing an overheated dog in cold water is vital to its recovery.

Then go to a vet, in a cooled car with the windows down or the air conditioning on, ringing ahead as you go, with someone still cooling the dog if you can. Go even if your dog seems to have recovered, because heatstroke can do harm that does not show at once. Our guide to what to do if your dog is ill or hurt on holiday explains how to find a vet quickly in a place you do not know, and it is worth saving the number of one before you need it.

A Closing Thought

The hardest thing about heat is that the dog will not tell you. It will follow you up the hill, chase the ball and trot along the promenade until the moment it cannot, because that is what dogs do. So the judgement has to be yours. On a hot day abroad, the kindest thing you can do is the least exciting: a long walk at dawn, a lazy afternoon in the shade, and another walk when the sun has gone. Your dog will think it was a perfect day.