6 signs of Heat Stroke in Dogs

As temperatures rise on warm spring days or during hot summer heatwaves your dog is more at risk of developing heatstroke (also known as heat-related illness, heat exhaustion, sunstroke or hyperthermia), but what causes it, how can you prevent it and what can you do to help treat an overheated dog?

What you need to know about heatstroke in dogs

Any dog can develop heatstroke, but some dogs, such as dogs that are large, energetic, overweight, have a thick coat or are flat-faced, are more at risk than others. Heatstroke can occur at any time of the year, but often happens when people walk their dogs on hot summer days. It is important that owners know the signs of heatstroke (heavy panting, tiredness and dribbling) and should urgently contact their vet if they think their dog is affected. 1 in 7 dogs treated by vets for heatstroke die. To give a dog with heatstroke the best chance of survival they need to be cooled down immediately and taken to a vet as soon as possible.

What is heatstroke?

Heatstroke happens when a dog’s body can’t cope with an internal rise in temperature. Dogs are not as good at dealing with high temperatures as us and can only sweat to cool down on areas not covered by fur, such as paws and noses. When they are hot, dogs mostly cool down by panting, but sometimes this just isn’t enough. As their body temperature rises it damages their tissues and organs, making them unwell. In severe cases, heatstroke can cause their organs to fail and can lead to death.

What causes heatstroke?

Heatstroke can be caused by a dog’s environment being too hot or by their muscles generating too much heat from exercise, or a mix of the two. Dogs are more at risk of developing heatstroke if they are without water, a good airflow or shade. Research has found that the common causes of heatstroke include:

  • Over-exercising, or exercising on hot days (around 75% of cases)
  • Not being able to cope in hot weather (around 13% of cases)
  • Being in a hot vehicle (around 5% of cases)
  • Being in a hot building (around 3% of cases)

Heatstroke most often occurs between May and August when the weather is warmer, but heatstroke from over-exercising can occur throughout the year. In very hot weather, even gentle exercise can lead to heatstroke, with nearly 70% of dogs with exercise-induced heatstroke becoming unwell after just going for a walk on a hot day. Dogs that are not acclimatised to hot weather, such as during a heatwave, or those that have travelled from a cooler location to a warmer one, are more likely to be affected.

What are the signs of heatstroke?

Dogs usually keep their body temperature at around 37-39°C, but as their internal temperature rises, particularly above 41°C, they start to show signs of heatstroke. The hotter the dog becomes and the longer their temperature stays high, the more damaged their tissue and organs become.

Signs of heatstroke can progress quickly and can include:

  • Heavy panting, even when not exercising
  • Breathing problems, particularly in flat-faced dogs
  • Tiredness
  • Stiffness or an unwillingness to move
  • Dribbling
  • Confusion
  • Being sick, can be bloody
  • Upset stomach, can be bloody
  • Not walking in a straight line
  • Collapse
  • Fitting

If you think your dog may have heatstroke it is vital that you immediately contact your vet while cooling them down. Getting early advice and treatment is essential to saving a dog’s life. Research has found that in the UK, although 1 in 7 dogs that are taken to vets with heatstroke die, 98% that are seen early with mild signs are likely to survive.

How can I help treat a dog with heatstroke?

Any dog with heatstroke should be seen by a vet, particularly if they are very unwell or unconscious. If you don’t know where your closest vet is, you can find a vet near you here. It is important that you start to cool your dog as soon as possible – this can make a big difference to whether they survive.

Tips on how to help a dog with heatstroke:

  • Stop them exercising, move them out of the heat and into the shade
  • Call a vet for advice
  • Lay them down on a cool floor
  • Offer them small amounts of water to drink
  • Carefully pour water over the dog’s body, or sponge them if water is limited. Particularly focus on their neck, tummy and inner thighs. Ideally continue to do this until their breathing returns to normal. Make sure the dog doesn’t inhale any water while you’re trying to cool them down
  • Fan them with cool air or put them in an air-conditioned room or car if possible. The impact of fanning them, or putting them somewhere that’s air-conditioned, will be greatest if they’re already wet

It was previously thought that rapidly cooling an affected dog could cause them to go into shock. This advice is now being questioned, so always speak to your vet who can guide you through how best to help your dog.

When is it too hot for dogs?

Heatstroke can happen at any time of the year, but since some dogs are less able to cool themselves down it’s difficult to say which temperatures are safe. Most dogs are comfortable at temperatures between 15-25°C, but this is very much dependent on their age, breed, size, coat length, amount of exercise their engaging in, health and fitness. Some dogs may struggle to maintain a low body temperature, even in lower temperatures.

Which dogs are most at risk of heatstroke?

All dogs can develop heatstroke, but some dogs may be more at risk than others. Research has found that dogs with a higher chance of developing heatstroke include those that are:

  • Overweight
  • Flat-faced
  • More energetic
  • Older
  • Bigger, particularly those over 50kg
  • Have longer or thicker fur
  • Have health issues, including being dehydrated or having heart or breathing problems

Breeds at increased risk include Chow Chows, Bulldogs, French Bulldogs, Dogue de Bordeauxs, Greyhounds, Boxers, English Springer Spaniels, Cavalier King Charles Spaniels, Pugs, Golden Retrievers, and Staffordshire Bull Terriers. 

More energetic dogs may have a higher risk of heatstroke because they are physically more active, and the heat generated by their muscles can contribute to a rise in body temperature. Older dogs may be less active, but age-related health issues may make it harder for them to control their body temperature. Bigger dogs, overweight dogs and dogs with longer or thicker fur may retain body heat more easily and so may find it more difficult to cool down. Flat-faced dogs, such as Bulldogs, French Bulldogs and Pugs, may find it harder to lose heat from panting, because a shorter muzzle means a smaller surface area to cool them down.

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