Helping Horses in Hot Weather

Most horses, even those working hard, can recover quickly from heat stress if they're cooled off properly and given rest, shade, good feed, and abundant fresh water.

Photo: iStock

By Charlie Powell, College of Veterinary Medicine

Equine specialists at Washington State University’s (WSU) Veterinary Teaching Hospital are urging Inland Northwest horse owners to be cautious with temperatures expected to hit or break 100°F again this coming week.

“Horses working hard in summer temperatures, especially if they are not well-conditioned, need access to abundant, clean water,” explained Jen Gold, DVM, Dipl. ACVIM, the veterinary specialist who heads WSU’s Equine Medicine Service.

“There is an old myth that still circulates out there in some circles that owners should withhold ice cold water from horses for fear it will induce colic,” she said. “That’s just not true according to numerous studies including the work done by veterinarians working with the equine Olympic athletes in 1996 in Atlanta.

“Fortunately, most horses, even those working very hard, will recover quickly if given rest, shade, good feed, and abundant fresh water.”

How can owners tell if their horses are getting too dehydrated? Gold says there are two simple tests anyone can master.

“The first is to look at the eyes and see if they appear dull or sunken,” she said. “The tissues and structures surrounding the eye will shrink some when a horse is dehydrated and the surface of the eye can become dull in severe cases. A conscientious owner who knows their horses will be able to see this easily and they should consider calling their veterinarian.

“The second test involves raising a horse’s lip and pressing your thumb against their gums to make a white spot,” Gold said. “Then release it. If it takes longer than four seconds or so for the blood to return, the horse may be dehydrated and should be offered free choice water right away. If a horse ever refuses to drink, contact your veterinarian immediately.”

Hard-working horses also lose electrolytes because unlike some animals, they have sweat glands all over their body. A horse’s normal cooling system works by first dilating blood vessels on the skin’s surface to radiate heat from the circulatory system. After that, they begin to sweat to increase evaporative cooling.

“Horses should have access to at least a regular salt block during hot weather because they typically do not get enough sodium or chloride in the forage and hay they consume,” said Gold. “All the other minerals they need otherwise they can usually get in their diet and again. Your veterinarian can advise what’s best in your area.”

What about bathing horses with cool water? “Absolutely, a horse will benefit from being hosed down and dried to help remove heat,” Gold said. “Most people have seen images of trainers washing off horses at a race track, so follow their lead and help your horse cool down the same way.”

When should a horse owner be concerned that a horse has become dangerously overheated?

“Heat exhaustion or heat stress is a serious condition that is potentially life-threatening,” said Gold. She said it’s vital to recognize clinical signs, including:

  • A core temperature of 104°F or above;
  • Rapid breaths or deep gulping types or respiration;
  • A lack of sweating and/or drinking;
  • Dry, dark, or dusky looking gums and mucous membranes;
  • An elevated “thready” pulse (meaning it’s weak and irregular); and
  • Depression, a dropped head, or lack of response to stimulation.

“In every case when this happens, a veterinarian needs to be involved with the horse’s care,” Gold said.

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