Summer is officially here and with it all the dangerous days of high heat and humidity.  You can do a lot to protect your horse from the dangers of working in the heat but first have to shed a lot of old wives’ tales that are simply false.

Accommodation to the heat takes time, and the weather often does not cooperate by providing a series of days of gently increasing heat and humidity.  As a general rule, a horse needs 7 to 14 days for the body to adjust to high heat.   This primarily involves increasing blood vessels in the superficial skin and directing blood to the skin surface so that heat can be dissipated.  The horse must also have an adequate supply of salt and water to keep body hydration levels normal and allow for repletion of water lost in sweat and through breathing.

Salt:  A salt block is not enough.  Provide minimum 2 oz of salt in feed or sprayed on hay in hot weather, with another 1 oz per hour worked in the heat.  If working 2 hours or more, or when sweating even in pasture is evident, also add a sweat replacement electrolyte product.

Water:  Clean water at all times is always a must. It’s not true that you can’t give a hot horse all they want to drink or they will founder or colic.  Horses should be allowed all the water they want both during exercise and after (ask any endurance rider!). Restricting water to sips while cooling out the horse has been shown to decrease total water consumption at the end.

Also not true that cold water drinking causes problems, although most horses prefer to drink water that is at normal body temperature rather than very cold.

H0sing:  Another myth is that hosing a hot horse with cold water is dangerous, e.g. will cause a heart attack.  Rapid cooling is critical to preventing heat related damage in horses.  The greater the difference between body temperature and water, the quicker the cooling will occur.  When horses are in dangerous heat stroke, even ice is used.

It has been claimed in some circles that using cold water will induce muscle cramps and that horses should be cooled out wearing coolers, even in hot weather.  Also not true.  If a horse has cramps after exercise there is a problem with muscle nutrition, hydration or mineral/electrolyte intake.

Common sense is also needed.  A horse that is not worked regularly should not be taken out and worked heavily on a hot day when the weather previously had been cooler.  Even a fit horse needs time to adjust to severely hot weather.

Eleanor M Kellon, VMD


About Dr. Kellon

Graduate of University of Pennsylvania Veterinary School. Owner of Equine Nutritional Solutions,, industry and private nutritional consultations, online nutritional courses. Staff Veterinary Expert at Uckele Health and Nutrition.
This entry was posted in Equine Nutrition. Bookmark the permalink.

One Response to BEAT THE HEAT

  1. abigail says:

    Another excellent article, your points regarding water ad lib for a hot horse are interesting, as I am currently studying my Stage 2 BHS they still make the assertion that horses should only be allowed to sip.

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