Heat Stroke in Horses: Signs and Emergency Cooling

By Dr Duncan Houston

A horse that remains intensely hot, breathless or dull after exercise needs attention immediately. Staggering, collapse or abnormal behaviour in the heat is an emergency, even if you have not taken a temperature.

Start cooling while someone calls the equine vet. The most useful first aid is prompt, sustained cooling, not waiting for the horse to recover on its own.

Quick Answer

Heat stroke occurs when overheating causes serious illness, potentially damaging the brain and other organs. Stop exercise, remove tack when safe, move into shade or airflow if nearby, and repeatedly apply plenty of cold water over the body. Cold or ice water is appropriate for a dangerously hot horse; do not delay cooling to scrape water off or avoid the hindquarters. Call your equine vet immediately for weakness, poor coordination, altered awareness or persistent distress.

Why horses overheat

Working muscles produce substantial heat. Sweating and airflow help remove it, but high humidity, intense exercise, poor ventilation and dehydration make cooling harder. Overheating can also occur during transport or in a hot stable without strenuous exercise.

Older, overweight or unfit horses, those with heavy coats and horses that sweat poorly need particular attention. University of Minnesota guidance on hot-weather care explains these risks and the importance of cooling and water access.

How worried should you be?

A temperature around or above 40°C after exercise is concerning if the horse is unwell or failing to cool, but temperature alone does not establish or exclude heat stroke. Do not delay treatment while searching for a thermometer, and never risk injury taking a reading from an unstable horse.

When is this an emergency?

Call immediately for neurological changes, collapse, severe weakness, distressed breathing or a hot horse that is not improving. Sweating does not rule out dangerous overheating, and an unexpectedly dry coat can also be a warning. Tell the vet the location, recent work or transport, weather, current behaviour and cooling already started.

Keep people out of the path of a staggering or panicking horse. A safe cooling area is more valuable than trying to force the horse into a particular stance.

What to do right now

1. Stop activity and remove saddle, harness and rugs when safe.
2. Use the closest safe shaded or breezy area; do not walk a distressed horse a long distance to find one.
3. Apply generous cold water repeatedly across the body. Use a hose or buckets and replenish warmed water. Ice water can help when available.
4. Use safe fans or natural airflow as an addition to water.
5. Offer drinking water if the horse is alert and swallowing normally. Never force water or electrolytes into its mouth.
6. Monitor behaviour, breathing and temperature if safe, and follow the vet's instructions on continuing and stopping cooling.

The FEI's cooling guidance supports repeated cold-water application without interrupting it to scrape. For a weak or uncoordinated horse, do not force walking. Follow the attending vet's direction.

What else could cause similar signs?

Fever from infection, colic, severe respiratory disease, exertional muscle injury and neurological illness can overlap with heat-related signs. A horse may have more than one problem. Cooling is appropriate for an overheated horse while the vet investigates the cause.

Veterinary care may include fluids, electrolyte correction and monitoring for muscle, kidney or other organ injury. Drugs and fluid volumes depend on examination findings; do not copy a treatment recipe or give painkillers without advice.

Recovery and prevention

A better temperature does not prove that internal injury has resolved. Follow the recommended rechecks and return-to-work plan. Report reduced appetite, dark urine, colic, weakness or new foot soreness during recovery.

Plan strenuous work for cooler conditions, reduce intensity when humidity is high, maintain water access and ventilate transport. Build fitness and heat exposure gradually. The FEI's Beat the Heat campaign also emphasises preparation of shade, cooling supplies and ventilation.

Common mistakes

• Waiting for collapse before calling.
• Avoiding cold water because of fear of shock or muscle cramp.
• Spending time scraping instead of continuing effective cooling.
• Forcing exercise or oral fluids into a distressed horse.
• Returning to work as soon as the coat feels cooler.

Frequently asked questions

Can I use ice water on a hot horse?

Yes. Cold and ice water can rapidly remove heat. Use what is available without delaying cooling.

Does a horse have to stop sweating to have heat stroke?

No. Serious overheating can occur with heavy sweating or inadequate sweating.

When can my horse work again?

After veterinary reassessment and an individual recovery plan, not a fixed number of days.

Recognise distress, start cooling and call early. Those three actions give an overheated horse the best chance of timely treatment.

ASK A VET™ can support follow-up care questions. Suspected heat stroke needs immediate hands-on veterinary help.