When a heatwave hits and the mercury soars, we all have this image in mind: our horse panting, desperately seeking shade, and wondering why we're putting it through this inferno. But rest assured, it's a bit more complex than just a thermometer reading 38 degrees Celsius in the shade. In reality, it's the formidable combination of heat and humidity that threatens equine health and makes our companions vulnerable. How many degrees can a horse actually withstand before its body starts to melt (not like ice cream in the sun, but almost)? The answer lies not only in the displayed temperature but also in a crucial heat-humidity index, a cocktail to be taken very seriously during periods of heat stress.
The heat-humidity index: the real thermal threshold to monitor to protect your horse
Imagine a thermometer that speaks in Fahrenheit because equine researchers have decided it's the universal language of four-legged suffering. The calculation is simple: take the temperature in degrees Fahrenheit, add the humidity percentage, and voilà, there's your index to keep a close eye on. Below 130, your horse can easily manage; between 130 and 150, it's time to ease off and monitor; above 150, your horse's sweating starts to go seriously wrong; and at 180 and above, it's a red alert: no exertion, mandatory rest. To give concrete examples for this French summer, a horse working in 32-33 degrees Celsius with 70% humidity is already in a very delicate zone, long before it becomes a veritable oven. Yes, so a very humid 30 degrees is worse than a dry furnace; it's the humidity that makes all the difference.
If you're hesitant to check these data before each session, remember at least one golden rule: when the combined temperature and humidity approaches 150, abandon the galloping gallop and opt for gentle heat management. Certainly, more fragile horses—older horses, horses with Cushing's or anhidrosis, those with very dark coats, or those that are overweight—are more prone to overheating.
How to recognize when your horse is becoming vulnerable to heat? The telltale signs
Horses don't check their medical thermometers or make obvious gestures when they're overheated. It's therefore up to us to be attentive to the signs: a resting heart rate exceeding 60 beats per minute, panting or even rapid and ineffective breathing, a sudden cessation of sweating indicating heat exhaustion, not to mention dark red mucous membranes and skin folds that fail to return to their original position – hello dehydration! And of course, a rectal temperature exceeding 40°C that doesn't decrease absolutely requires immediate veterinary attention. These indicators remain the essence of good monitoring during a heatwave, far removed from clichés and misconceptions.
Heat management: preventing heatstroke in horses during heat waves
Rather than waiting for the temperature to soar, it's best to adopt simple and effective measures. Working early in the morning or in the evening, avoiding strenuous work between 11 a.m. and 5 p.m., ensuring optimal hydration with fresh water, and providing ample shade, not just a lone tree, are essential steps for heatwave prevention. Transport also deserves special attention: the horsebox or truck must be properly ventilated, departures should take place during cooler hours, and horses should never be left standing in the sun, even for five minutes.
Certain methods, such as clipping for hairy horses or those with Cushing's disease, also improve their heat tolerance. For the most resilient horses, or those that work hard, the use of electrolytes is recommended to compensate for losses due to intense sweating. The key is also to gradually acclimate your horse to higher temperatures, because proper heatwave acclimatization is far better than fifty buckets of cold water!
Heatwave emergency: act quickly to avoid tragedies
When the inevitable heatstroke strikes, the first instinct is no longer to wonder about using cold water that might cause cramps. The latest research—supported by the International Equestrian Federation—recommends thoroughly and continuously dousing the horse with cold water, everywhere, including between the hind legs. Quickly finding shade, a cold shower, plenty of water, and an immediate call to the veterinarian as soon as the temperature approaches 41°C (106°F): these are the keys to effective treatment.
In this fight against the heatwave and its impact on equine health, in addition to monitoring vital signs, vigilance remains the best defense. To learn more about the heatwave protection strategy or understand the risks associated with heatstroke in horsesMany reliable resources exist. By following these few rules and adjusting your heat management, you will allow your horse to get through heat waves with less stress and maximum comfort.