Understanding Heatstroke in Horses
Updated: Jun 30, 2022
Horse riding can be on top of your favorites list in summer; however, riding in scorching summer can put your equine friend in a dangerous zone. A horse produces a lot of heat during feed digestion and exercise, adding to the hot weather. If the heat produced by the horse's body overwhelms his cooling system, the horse becomes prone to heat illness. And consequences can vary from neurological signs to fatal heat stroke.
For an equestrian, it is essential to understand what care a horse need while exercising in summer. Heat stroke is a common health problem of horses faced by many horse people. Let's look deeper at the development of heat stroke, its signs and preventive measures.
How does heatstroke develop in horses?
Most animals, including horses, maintain a specific body temperature. For a horse, the normal body temperature is 99 to 101°F. When the body temperature of a horse surpasses this limit due to hot weather or strenuous workout, horse thermoregulatory systems work to cool it down. How equine thermoregulation works? When the body temperature of a horse decreases or increases from the normal physiological range (99 to 101°F), thermosensors in the muscles and spinal cord send messages to the hypothalamus, a part of the brain. The anterior part of the hypothalamus controls the horse's body temperature by several physiological changes; in response to high body temperature, cardiac output and blood flow to the skin increase, which act as a major heat-dissipating organ.
Sweating is also a major mechanism that causes the evaporation of water from the body and results in cooling. Your horse may be at extreme risk of heatstroke if he is a non-sweater. Anhidrois is a condition where the horse is unable to produce sweat to cool naturally. It is important to support your horse when he is unable to produce sweat.
In combination with high temperature, when the relative humidity increases from 75%, evaporation of sweating does not occur, and the horse's body temperature keeps rising continuously. When the temperature increases to 106°F, a horse may start stumbling, and breathing heavily, including heat exhaustion leading to heat stroke.
Heat stroke damages the body by denaturing different proteins and cellular membranes at the cellular level. A variety of heat shock proteins are also released by the body to resist heat stress. In case of a further increase in temperature, the death of cells occurs.
Causes Of Heat Stress & Heatstroke in Horses
Poor Ventilation
Good air exchange and proper ventilation are crucial for horses in hot summer. Horses that remain exposed to the sun or live in poorly ventilated barns become more prone to heat stroke.
A sound ventilation system keeps the barn cool and controls moisture. When sufficient air exchange takes place, it exhausts the fumes, ammonia and pathogens from the air. In this way, barns remain cool and good air quality is maintained.
High Temperature and Humidity
When the moisture level of the air increases, it feels hotter than the actual temperature. That's why an increase in humidity plays a critical role in developing heat stroke in equines. An apparent reason is that the horse is the only mammal other than a human that uses sweating to reduce its body temperature. During hot and humid weather, evaporative cooling due to sweating does not occur, and the horse heats up.
How do the high temperature and relative humidity affect horse thermoregulation? Here is the University of Minnesota heat index chart.
Strenuous Exercise in Summer
Consider morning or evening time for the exercise or training of your horse. Strenuous exercise increases the horse's temperature by several degrees; however, the horse efficiently dissipates 97% of this heat to maintain its temperature. Due to any reason, if a horse cannot dissipate the heat, his temperature can rise by 15°C in an hour.
Dehydration and Electrolyte Depletion
As mentioned earlier, sweating is the only mechanism a horse can use to cool its body. And horses lose a lot of water and electrolytes during sweating. So, dehydration can be the foremost reason for heat stroke in horses.
An average Quarter horse used to drink 8 to 10 gallons of water in a day. And in summer, this requirement nearly doubles. This requirement can vary with the activity of the horse. It is estimated that a horse loses 4 gallons of water in sweat for one hour of workout. Sodium and potassium are the major electrolytes a horse loses during sweating, and their depletion can hamper muscle functioning, acid-base balance and fluid regulation.
Signs of Heatstroke
Here are some common signs observed in horses suffering from heat stroke.
Stumbling and loss of balance
Profuse sweating or no sweating in severe cases
Convulsions and neurological signs
Very hot and dry skin
Rectal temperature between 102 to 106°F
High heartbeat (>50 beats/min) and rapid breathing (>20 breaths/min).
Dehydration, loss of skin elasticity, sunken eyes, and cessation of urination.
All these signs indicate heat stress in horses; if these signs persist, they lead to heat stroke. A more complicated situation develops when sweating stops, the horse starts breathing rapidly, and body temperature surpasses 106°F. If heat stroke is not caught on time, the horse may collapse, go into convulsions and die.
How to prevent heatstroke in horses?
Here are a few things you need to consider as preventive measures for heat stroke in your horse
Ensure that your horse has access to shade and a well-ventilated barn. Well-spread air inlets can make a good air exchange and keep the good air quality in the barn.
Your horse should have free access to fresh and clean water. Keep in mind that the water requirement of horse increase two-fold in summer. Supplementation of electrolytes is also necessary to replenish the electrolyte reserves.
Acclimatizing your horse to exercise in hot weather can help a lot. Different horses can respond to heat stress differently. If you adapt your horse gradually to work in hot weather, he will become somewhat adaptive to the environment.
Take special care during exercise and post-workout. Keep an eye on the horse's breathing rate and level of sweating. Cool down your horse after a workout by walking to the barn. And immediately shower plenty of water on a horse, and try to cool down the body areas with large veins like the neck and inside of the thighs.
Avoid riding your horse near feeding times. The heat produced from exercise and feed digestion can accumulate and make the horse susceptible to heat stress.
Consider hair clipping in summer. The hair coat can trap the horse's heat and play a role in overheating the horse. Clipping your horse in summer can also aid heat dissipation.
Preventing Heatstroke in a Holistic Way
Your horse can benefit greatly by also supporting the natural abilities to protect itself. Acupressure points are amazing to use as an everyday preventative care.
Benefits of acupressure:
Support the immune system
Encouraging sweating
Clearing summer heat from the body
Naturally balancing body functions
Decreasing any inflammation
Increase water absorption
Below is acupressure point GV14. This point has so many benefits for the horse.
Location: In the depression on the dorsal midline right in front of the highest point on the withers. It is between the 7th cervical and 1st thoracic vertebrae.
Benefits: any cervical issues, convulsions, fever, heatstroke, wobblers, forelimb disorders, calms the spirit (spookiness), clears the brain (for focusing), tonifies protective chi, and facilitates chi flow.
Pressure: you can hold this point gently for 30-45 seconds a day. You can also massage the point with your fingers. This will stimulate blood flow and chi to the area. You can also use this point while on horseback when your horse shows spookiness on the trail. You can often see horses grooming each other in this location. Horses naturally support each other!
Acupressure is a preventative and complementary care option. If your horse is experiencing heatstroke or any abnormal behaviors, call your veterinarian. You can use acupressure points safely every day to provide your horse natural support, but it is not a replacement for veterinary care.
Contact us today to set up routine sessions for your horse. You can also attend our equine clinics to learn more about how acupressure works, the benefits, acupressure techniques, what to look for in your horse, and more! Sign up for our monthly newsletter to see our upcoming events!
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