Heat stress: what is it and how to stop it

A reaction to a bout of intense exercise in hot weather is called heat stress. Colin Mitchell MRCVSanswers your questions on how the reaction develops


Q: Will my horse suffer heat stress when the weather warning signs hit?

Colin says...

Not exactly. Your horse will have to be doing strenuous work for symptoms to occur.

It’s unlikely your horse will go down with heat stress just by overdoing the sunbathing in his field.

Heat stress is a combination of hard work and hot weather. It’s all to do with how efficiently your horse loses heat while exercising.

Q: Is there any difference between heat stress and heat exhaustion?

Colin says...

Some vets say that heat exhaustion shows the beginning signs of heat stress, with the horse showing fatigue and heat stress being the later development. Basically, they come under the same banner.


Q: Are specific types of horses more prone to heat stress?

Colin says...

It’s not uncommon for racehorses to suffer heat stress because of what their bodies are put through when they race.

This is why you’ll often see a team of people on standby with buckets of water ready to soak their horses after they’ve crossed the finish line. 

Q: Is there anything I can do to help my horse lose heat more efficiently?

Colin says...

Essentially it comes down to fitness. The fitter the horse, the more efficiently he’ll lose heat because his body will know what to do.

However, even the fittest horses in the world (such as racehorses) can suffer heat stress if they’re overworked in hot, humid conditions.

How quickly you deal with the symptoms when they arise is the main consideration, rather than preventing it.

You’ll need cold water, shade, a breeze and the help of a vet, so if you think your horse is showing symptoms of heat stress, then get a vet involved ASAP. 

Read more about heat stress in our 441 issue of Your horse magazine - order your copy here

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