Riverina Equine Vet



Heat Stress

With temperatures on the rise, is important to remember that the very same warm and sunny weather we so much enjoy can be quite difficult for our horses to cope with. A horse must expend considerable energy just to keep cool as temperatures climb. This of course doesn’t mean that you can’t enjoy your favourite equestrian activities on these hot days, you will just need to take precaution and be vigilant in watching for the earliest signs of heat stress in horses.

Commonly observed signs of heat stress include:

  • Profuse sweating or no sweating (anhydrosis)
  • Rapid respiratory rate (>20 breaths/min)
  • Rapid heart rate (>50 beat/min)
  • High rectal temperature (>38.5°C)
  • Dehydration – can be detected through a skin pinch test. Simply pinch some skin on the horse’s neck and it should resume to its original position immediately after it is released. If it collapses slowly, the horse is dehydrated.  

Horses that perform at high levels such as Thoroughbreds, Standardbreds, endurance and other performance horses will of course be influenced by heat stress during their training and competition. However, high performance horses are not the only ones at risk. Foals, especially the very young, have poor thermoregulating ability - they can overheat simply standing in the very hot sun. Add to this some activity, such as following an upset mare up and down a fence line and a serious problem can quickly develop. Horses in poor ventilated barns or stabled horses on high grain diets (excess heat produced during digestion) are at higher risk of suffering from heat stress.



Veterinary attention should be sought if horses have breathing difficulty, appear distressed, become weak, develop diarrhoea, show signs of mild colic or stop sweating. You should immediately move the horse into shade and hose or sponge it with cool water. Direct the hose to the inside of the legs, head and along the neck where large blood vessels are located near the surface. Encourage the horse to drink cool water in small amounts frequently.



Ensure that your horse has ready access to ample shade and cool clean water during hot days. If possible, strenuous exercise should be avoided or limited to the coolest parts of the day i.e. early morning or late evening. If your horse is housed in a stable, ensure that there is adequate ventilation. Avoid over rugging your horse or limit rugs to lightweight natural cotton materials that ventilate well. It may be beneficial to offer water with electrolyte additives before and after exercise, however always give the horse an option of plain water or electrolyte water as some horses can be fussy.