Heat Stress

by Sonnie Olin with Joe Noble, DVM

Most of us know how to take care of ourselves in extreme heat, but do we know how to care for our horses? Even though most horses can function and take considerably more heat than most of us, the methods of measuring and monitoring the extreme heat for human safety are an equally important tool for monitoring the safety of our horses.

Here are some preventive measures you can use to protect your horse in extreme heat and also some emergency actions to use in case of a heat-related emergency.

Water. A major concern during extreme heat is water supply. A horse is no different than a human. In fact, having large amounts of clean, fresh water may be even more important for his body and intestinal tract’s regularity than it is to our own.

Salt. A second concern is salt balance. Everyone knows we need salt in our diet, but perhaps not everyone realizes how important salt is to a horse. Salt blocks are a common source of salt for horses and cattle. But did you know there is a difference between the tongues of horses and tongues of cattle? A horse’s tongue is softer and not quite as rough as a cow’s tongue. Because of this difference, it may be more difficult for a horse to lick enough salt off a block to get the amount he needs. This is particularly true of horses who don’t like to rub their tongues against the hard salt blocks. Loose, trace-mineralized salt may be given free choice.

Electrolytes. Another option in regard to salt balance is to supplement your horse with electrolyte powders or electrolyte mixes or pastes. Some pastes and mixes have a strawberry or orange flavor and are simple to use. Select the flavor that your horse prefers and sprinkle it on his feed, usually twice a day.

Some owners prefer to give electrolyte solutions after a horse has performed, particularly if he has gone through a really strenuous performance and lost a lot of fluids.

Rations. Cutting down the amount of grain you feed during periods of unusual stress is another recommendation. The majority of horses hauled frequently (frequently is the key word here) do very well even when there is no change in their diet. You can restrict the amount of grain or remove the grain completely from a horse, all at once, but do not take it away for a day and then throw it back in front of him all of a sudden. It is recommended that you cut feed back to half-rations a couple of days after you get home before slowly starting to increase the grain until you reach a full ration.

Ventilation. The heat index provided for humans, taking into account both temperature and humidity, is just as important to your horse as it is to you. Horses can get used to heat and humidity. Even so, if you have spent any time in an enclosed trailer or stall, you realize the effect heat and humidity have on temperature and air quality in those areas.

Vents and windows can be opened in a horse trailer to increase air-flow. If a stall does not have adequate ventilation, you may need to hang a fan or maybe two – one in front of the stall and one at the top of the stall. It is also beneficial to get your horse out of the stall occasionally and into a cool breeze.

Work. Some individuals can be worked in the hot sun for several hours and never have a problem. Whereas, a horse who may be less conditioned to the heat or more sensitive to the heat … not so much in less condition, but just more sensitive to the heat … or not in as good condition as other horses … only 30 to 45 minutes of hard riding, especially in deep sand or soft ground, can get those horses into trouble rapidly. The key to avoiding problems is to know your horse as an individual and be aware of his physical condition and capabilities.

Cooling Out. Walking your horse for about 8 to 10 minutes before you hose him after a hard workout is recommended. It usually takes approximately 20 to 30 minutes for a horse to get back to normal. During the cooling-out period, it is OK to give small amounts of water, but putting a horse back into a stall with full feed is not recommended. Each horse is different; you need to adapt what you do to fit your particular horse and his needs.

Heat Stress. The signs of heat stress usually come in a group or all at once. The horse’s respiratory rate will usually increase until the respiratory rate is higher than the heart rate. One of the first signs a horse is heat-stressed is that the horse is so hot that he begins panting. A horse will also stop sweating or will not sweat as much as usual. The mucous membranes on the inside of the mouth will be dry and somewhat pasty. A horse may show signs of colic or intestinal cramping, and may even show some signs of tying up or muscle cramping along with it. If horses show these symptoms, they are showing signs of heat stress and need prompt veterinary care. Without veterinary care, some horses will go into shock and may not recover.

If your horse is heat-stressed, try to get the horse to drink an electrolyte solution or straight water – taken in small amounts slowly over a period of time. Hosing off a heat-stressed individual is also recommended to help the cooling down process.