As temperatures soar, remember to take weather conditions into account when planning a ride.
Working horses during very hot and/or humid weather can be potentially dangerous for both horse and rider. Humans and horse both rely heavily on their ability to sweat to cool their bodies during exercise. Respiratory cooling (puffing or blowing) also helps us cool down but horses and humans rely less on this method of cooling than dogs who cool by panting. Cooling by sweating and respiration is effective when humidity is low and breeze is present. Hot, humid, still weather conditions make it much harder for our core temperature to cool back down to a safe level.
The normal rectal temperature of a horse lies in the range 37.0 to 38.0 degC. Once this temperature exceeds 40 degC the horse should be cooled down. If the core body temperature becomes too high (42 degC) the horse will suffer from heat stress (hyperthermia).
Some horses that have been exercised too hard, too often under hot, humid conditions develop anhidrosis. Horses suffering from this condition permanently lose the ability to sweat sufficiently to regulate their body temperature.
Many official Equestrian sporting organisations around the world now use the Wet Bulb Globe Temperature (WBGT) Index to decide whether competitions should be run or cancelled due to the risk of overheating horses and riders. As individuals riding at home, we also need to make sensible decisions about how much work we can safely subject ourselves and our horses to during hot, humid weather.
When a horse must be worked during very hot weather, try to ride in the coolest and least humid part of the day and reduce the length and intensity of the training. If it’s really hot and humid, and you’re not going to Nationals next week consider whether you really need to ride today. Your horse isn’t likely to give his/her best performance while heat stressed, nor will you be riding at your best!
It is important to provide shade and preferably a breeze (this can be supplied by a fan) for horses in their paddocks, yards or stables during very hot (especially hot, humid) weather. Shade and hosing with a breeze (or fan) during recovery from exercise helps to reduce core temperatures quickly.
Horses need salt everyday (approximately 10g of salt per 100kg of bodyweight) to maintain correct sodium balance and need even more if they sweat. Salt is usually added to pellets and grain mixes designed for horses, so you will need to count this salt in calculating how much plain salt per 100 kg target. You will need to add extra salt as well during very hot weather or following heavy exercise.
Free choice access to loose salt is also advisable. Sweating horses can lose as much as 10 to 15 litres of fluid per hour. Dehydration occurs if this liquid is not replaced. However, it is not as simple as just adding water. The fluid in our bodies contain various salts called electrolytes (sodium, chloride, potassium, calcium) which help manage the hydration of individual cells and blood volume.
The water and electrolytes lost in sweat will be effectively replaced over the course of a few days rest as the horse drinks water and eats an electrolyte-enhanced diet containing extra salt and adequate macro-minerals. However, an electrolyte solution can speed up recovery for a heavily sweating horse and is particularly important when the horse has to perform again on the same day or the following day.
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