Beating the heat

With summer upon us and temperatures soaring, horses and riders are in danger of overheating. Excessive sweating can lead to an imbalance of electrolytes and dehydration as the horse loses fluids from his bloodstream. Humid conditions exacerbate the problem. Riding attire, which is designed with comfort and safety in mind, puts the rider at risk as well.

What happens to your horse’s body?

More than 50% of the energy used for a horse’s muscular activity is converted into heat, and in hot and humid weather he cannot always sweat enough to cool himself down. Once your horse has started to dehydrate, he will be less able to control his body temperature and this can result in heat exhaustion, particularly if the oxygen requirements of the muscles are not being met.

Check the following if you suspect your horse is dehydrated or has heat exhaustion:

  • Pinch a fold of skin on the shoulder between your fingers. It should snap back into place immediately on release.
  • Dark urine.
  • A dull expression.
  • Elevated body temperature (above 39°C).
  • Dark or discoloured gums.
  • A weak, irregular or elevated heartbeat.
  • Rapid, shallow breathing.

Heat exhaustion can result in muscle fatigue and cramps, and in severe cases damage to the heart and kidneys.

Cooling down

There is much you can do to help your horse if you suspect he is overheated.

  • Walk for a couple of minutes after you finish your workout to reduce the chance of blood pooling in the muscles.
  • Hose him down with cold water. Make sure to scrape off the warmed-up water and keep hosing till the skin feels cool to the touch.
  • If possible, stand him in a breeze (in the shade) or under a fan.
  • Encourage him to drink as much as possible.

If his rectal temperature is not back to normal (37.2 to 38.3°C) within an hour, don’t hesitate to call your vet who can administer intravenous fluids and electrolytes to restore hydration and normalise blood chemistry.


Current weather conditions are quite extreme, and there was a very quick transition from cold winter nights to punishing summer heat. Horses who weren’t clipped and are still carrying their full winter coats would be in danger of overheating, as the thick hair keeps in excess body heat. Similarly, overweight horses with layers of fat beneath their skin cannot dissipate heat effectively. The raised heart and respiratory rates of unfit horses are also likely to cause heat stress, and so a fit horse at ideal weight (see HQ issue 111, June 2016) with a light summer coat will be more able to cope with these demanding conditions.

Horses lose minerals such as sodium, chloride, potassium, magnesium and calcium as well as water when they sweat, and supplementing with electrolytes is very beneficial in restoring the balance. This can be given in the form of a powder in his food and is recommended for horses competing in hot, humid conditions or travelling long distances.

Coping with the heat

Once temperatures go above 25°C, special care needs to be taken to keep your horse comfortable.

  • Make sure there is shade in his paddock.
  • Bring him inside between 12 and 2pm (but also avoid leaving him out during early mornings and evenings when the midges are about and he is at risk of contracting AHS).
  • Watch for signs of sunburn on light-coloured areas. Apply sunscreen or make sure he has a fly mask and fly sheet, which has the added advantage of reflecting the sun’s rays.
  • Ensure he has access to fresh, cool water at all times. Algae and bacteria grow rapidly in warm water so clean water buckets regularly.
  • Provide salt in his diet.
  • Install an overhead fan in his stable.

Text: Jan Tucker

The full article appears in the December issue (117) of HQ magazine > Shop now