The typical first signs of heat stress in horses will include behavioral changes, such as lethargy and weakness, said Dr. Alison M. LaCarrubba, DVM and clinical instructor of equine ambulatory medicine at the University of Missouri’s College of Veterinary Medicine. “They will also show exercise intolerance and general listlessness when asked to work.”
If an owner thinks their horse is overheating, LaCarrubba recommended checking the animal’s rectal temperature. “The normal temperature of a horse will be less than 102 degrees Fahrenheit,” she said. “When the rectal temperature is above 104-105 it is best to cold hose the horse and then repeatedly wipe the excess water off with a sweat scraper and hose again until temps come down. If you leave the hot water on the horse or put wet towels on the horse it will act as insulation and keep the temperatures up.”
Dr. Lyndi Gilliam, DVM and DACVIM, is an assistant professor of equine internal medicine at Oklahoma State University’s Department of Veterinary Clinical Sciences and the Center for Veterinary Health Sciences.
Gilliam said that horses may have excessive sweating; however, some horses will experience a syndrome called anhidrosis when the heat and humidity rise. “In this case the horse will be unable to produce sweat and they will over heat very rapidly. If your horse is not sweating on a hot day this is cause for concern.”
Heat stress can be prevented by ensuring horses have access to well ventilated, shaded areas and access to plenty of fresh water. “Water should be shaded to avoid the water becoming too hot discouraging horses from drinking,” Gilliam added.
If the horse’s water source is a creek or pond the owner will need to be very mindful of the water level and quality. “Often as summer progresses pond water levels decrease and the water becomes less palatable to horses,” Gilliam said.
Encouraging adequate water consumption is essential. “Horse owners should make salt available to horses in the summer as many electrolytes are lost during sweating,” Gilliam said. “When exercising horses in the summer electrolyte supplementation may be needed and they should contact their veterinarian for specific recommendations.”
LaCarrubba suggested that if you provide electrolytes, to provide it only in a bucket in case the horse is not inclined to drink the electrolytes. There should also be another tank or source of cool water without the electrolytes.
For owners of geriatric horses, it is important to pay careful attention to their haircoat. According to Gilliam, if the horse has not adequately shed its winter coat the horse should be body clipped.
Heat stress can also be avoided by riding during the cool times of the day, either first thing in the morning or last thing in the evening. “The horse can be sponged down before and then after riding as well,” LaCarrubba said.
Horses should also have access to shaded areas with good ventilation, fans and misting systems to help keep them at a normal and cooler temperature.
“A cool area, a cool drink, protection from insects and reasonable rests from exercise during the heat will go a long way in keeping people and horses happy and healthy this summer,” Gilliam concluded.
For more information about equine heat stress prevention and care, contact your local veterinarian or equine extension specialist.
