In this episode of the Disease Du Jour podcast, Christine Staten, DVM, MBA, joined us to talk about heat stress and heat stroke in horses. She explained the difference between heat stress and stroke, discussed clinical signs, and provided an overview of different management options.
Heat Stress vs. Heat Stroke in Horses
Staten said horses experiencing heat stress show clinical signs such as abnormal sweating, faster breathing, stress, exhaustion, dehydration, and elevated body temperature. However, these horses tend to recover normally once they are cool. “Whereas when we’re talking about heat stroke, what we’re really dealing with is a horse that needs significant help to get better,” said Staten. “Their body physiologically is very stressed, and it can certainly lead to death.”
Horses experiencing heat stroke generally have a body temperature over 106 degrees. They can collapse, become nonresponsive, and have convulsions.
Risk Factors for Heat Stress and Heath Stroke in Horses
One of the main factors for heat stress in horses is the heat index. “If you add the temperature to the humidity and that number is over 150, the risk of having a heat-related problem in a horse is extremely high,” Staten said. Therefore, horses in hot, dry climates are less at risk than horses in humid climates.
Staten said acclimation is important for horses moving to hot climates. Horses that are morbidly obese are at an elevated risk, as are horses with uncontrolled PPID or anhidrosis. “They’re probably going to need more management of their actual disease process and the lack of sweating,” Staten said of these compromised horses.
Managing Horses With Heat Stress and Stroke
While some horses with heat stress can recover without veterinary intervention, Staten recommends treating any horse showing visible signs of impairment due to heat emergently. “It can progress to heat stroke very fast, and it’s hard to tell which ones are going to get better and which ones are going to go into that more life-threatening heat stroke,” she said.
Management options for heat stress and stroke are similar, though the prognosis is much better for horses with heat stress. It primarily involves cooling the horse down with cold water or ice and rehydrating them. Staten recommends focusing on areas with large vessels close to the surface, such as inside the legs. She has had success with soaking a bed sheet in ice cold water and laying it over the horse as an evaporative cooler. The owner should start this intervention while they wait for their veterinarian to arrive. The veterinarian can then start the horse on IV fluids.
Horses will likely need electrolyte supplementation, and they should have access to water. They should be in an area with good ventilation and have a fan on them. If the horse is down, the veterinarian can use anti-inflammatories to improve their comfort.
The prognosis for heat stress is generally very good, and the horse can rebound within an hour. For heat stroke, Staten said the prognosis for survival is likely poor, especially if the horse is collapsed.
Following an episode of heat stress, Staten said it is important to determine why the episode occurred. Does the horse need shade? Is the barn poorly ventilated? Was the horse transported on a hot day? Is the horse fat, or does it have an endocrine disease? After stabilizing the horse, Staten generally rechecks him the following day and works with the owner to develop a plan to prevent the situation from happening in the future.
Preventing Heat Stress
Staten described some strategies for preventing heat stress in horses. These include acclimating the horse properly to the conditions, riding in the early morning or evening, and monitoring the horse for signs of dehydration, which might cause their urine to become dark and concentrated. Owners should provide horses with multiple containers of water in the pasture, and they can throw treats in the water to encourage their horses to drink more. If the horse has an endocrine disease, it is important to get their condition under control before putting them back to work; Staten sees heat stress most frequently in horses with uncontrolled Cushing’s disease. Clipping older horses with shaggy coats can also help prevent heat stress.
About Dr. Christine Staten
Christine Staten, DVM, MBA, is a native of Tucson, Arizona, and after an earlier career as an OB-GYN technician, she attended and graduated from Colorado State University School of Veterinary Medicine in 1999.
Staten joined Barbara Page, DVM, in 1999 as a part of Tortolita Veterinary Services, a large animal ambulatory practice. In 2005, together they built a new mixed-animal clinic on the eastside of Tucson called Adobe Veterinary Center. She is an active member of the Southern Arizona Animal Cruelty Task Force. Although she enjoys all aspects of large animal medicine, she has a particular passion for endocrine disease, dentistry, reproduction, and preventive medicine. She prioritizes owner education and believes it leads to healthier medicine.
At the age of 50, Staten went back to school for her MBA. She then founded Veterinary MBA, which provides real-world business education and resources for veterinary practice owners.
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