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Standlee Premium Western Forage

Dealing with Heat Stress in Horses

Girl washing Horse

Your horse is an organic oven of epic proportions. Simply put, they produce a ton of heat. After just a mile of riding, your horse creates enough warmth to boil 2 whole gallons of water. While a horse’s body can usually regulate their temperature, the hot summer months make this more difficult. High temperatures, high humidity, lack of air movement, poor ventilation and dehydration, all increase the dangers of a serious heat-related problem known as heat stress.

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Signs of Heat Stress

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As a horse exercises, their muscles turn energy into movement. But a horse’s body isn’t 100% efficient. Part of this energy is lost in the form of heat. The rate at which a horse produces heat is proportional to how hard their muscles are working. The harder a horse has to work, the more heat they produce. If horses didn’t have the ability to regulate their heat, their body temperatures would increase by almost 60°F. Basically it’d be like riding a hot potato. Fortunately horses can dissipate around 97% of the heat they produce. To regulate their body temperature, a horse will increase their sweating rate, move more blood to their capillaries (blood vessels near the surface of their skin) and increase their rate of breathing in an effort to release any heat build-up.

Heat stress occurs when a horse can no longer properly regulate their body temperature. The symptoms to look for consist of profuse sweating (or even no sweating at all), rapid breathing (more than 20 breaths a minute), rapid heart rate (more than 50 beats a minute), dry/hot skin and an unusually high rectal temperature (greater than 100.4°F).

Heat stress can also cause a horse to become dehydrated. An easy way to tell if your horse has become dehydrated is by pinching the skin on their neck. Usually, their skin should resume its normal position immediately. However, in a dehydrated horse, their skin will take a while to resume its normal position.

If the initial signs of heat stress go unnoticed or uncared for, more serious complications can arise. Your horse could start breathing with great difficulty, appear distressed, stop sweating, become weak or develop diarrhea or signs of colic. These symptoms are serious and need immediate attention. A vet should examine your horse as soon as possible to provide medical treatment.

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Treating Heat Stress

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As mentioned, horses displaying any of the more serious signs of heat stress should be examined by a vet as soon as possible. You should immediately get your horse into shade and hose or sponge them off with cool or even cold water. It’s most important to hose the insides of the legs, head and neck areas where large blood vessels are located near the surface of their skin.

Use fans and encourage your horse to drink. It may take an hour or more to get all their vital signs back to normal. Horses that have seriously overheated tend to be more susceptible to overheating in the future. If your horse has suffered a serious heat stress episode, they should have 10 to 14 days of rest with some turnout and a gradual return to work.

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Avoiding Heat Stress

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Most horses adapt to summer weather if given time to adjust gradually. However, some horses will be more susceptible to heat stress than others. Performance horses such as thoroughbreds, Standardbreds, endurance and other performance horses will be influenced by heat stress during their training and competition. But high performance horses aren’t the only type to be at risk.

Foals have very poor thermo-regulating abilities. They can overheat simply by standing in the hot sun. Likewise, overweight horses that aren’t use to regular exercise are also at greater risk.

Environmental factors can also play a role in how susceptible your horse is to heat stress. Horses stabled in badly ventilated barns and fed poorly digestible forage will produce a lot of heat during digestion, making them more prone to heat stress. Additionally, any horse that doesn’t have access to salt and electrolytes will be at a greater risk.

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Nutritional Contributions to Heat Stress

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A racehorse will lose up to 2.5 gallons of sweat per performance (work/race). That doesn’t mean just water, but also a lot of salt (which is referred to as electrolytes when broken down into its chemical components). Electrolytes are used to get nutrients into a horse’s cells and the cell’s waste products out. This makes them responsible for getting nerves to fire and muscles to contract. In order for these biochemical reactions to proceed properly, a horse’s fluids need the right amount of electrolytes.

Your forage can also contribute to heat stress in your horse. Certain feeds create more heat when digested than others. During hot conditions, it’s important to include highly digestible fiber sources such as beet pulp to decrease the thermal load of digestion. Standlee Premium Western Forage offers a variety of excellent quality forage products, which provide increased digestibility. To learn more about these products, check out the link below.

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