Beating the heat
Aug 07, 2023
Summer heat and humidity are challenging for both horses and horse owners. Helping equine cope with the heat is important for their comfort and optimum athletic performance. You might be surprised to learn that horses are less tolerant of high temperatures than humans. This is because horses have a larger body mass to surface area ratio than humans, which means they have to dispel more heat per square inch of skin than humans in hot conditions.
Animals’ bodies function best within a very narrow temperature range. Thermoregulation is the process by which the body maintains optimum core temperature (99-101°F for adult horses). Heat is produced as a result of many biological functions, including muscle contraction and metabolism. Excess heat must be transferred from the horse to its environment to maintain body temperature. Heat is transferred from one object to another by four primary mechanisms: conduction, convection, radiation, and evaporation. Conduction occurs when heat is transferred from a warmer object to a cooler object through direct contact; for example, when you touch a hot stove, heat from the stove is transferred to your hand.
Convection occurs when heat is transferred through a liquid or gas, such as the loss of body heat to the atmosphere in cold weather; air movement, via wind or fans, increases the rate of convective heat loss. Radiation is the transfer of heat from one object to another without direct contact; we can feel this effect when we step outside on a bright, sunny day. Evaporation occurs when heat transforms a liquid into to a gas; sweating and panting are both examples of evaporative heat loss mechanisms in animals. Horses produce copious amounts of sweat, especially during exercise, as an effective means of reducing their body temperature.
If horses are less tolerant than humans, does that mean we shouldn’t ride our horses during the summer? Of course not! However, you should be mindful of the extra stresses horses are under during hot, humid weather so that you can make sure your horse stays as comfortable as possible. A simple measurement of comfort in hot weather is the heat index system. A heat index is calculated by adding the air temperature (in °F) and the relative humidity (in %). The heat index is similar to a wind chill factor in winter weather; it gives us information about how comfortable – or not! – outdoor conditions are likely to be. While there are no hard and fast rules about heat index values and equine comfort, there are some generally accepted guidelines that are useful for horse owners.
When caring for very hot horses, the primary goal is to reduce their body temperature as quickly as possible. The best way to do this is by repeatedly applying cold water to the horse, ideally while either walking the horse or standing it in front of a fan. This technique maximizes multiple cooling mechanisms: conduction (cold water absorbs heat from the horse’s skin), convection (moving air allows more heat loss from the horse than still air), and evaporation.
Scraping the excess water from the horse between water applications is not necessary and will actually slow the rate of heat loss, as both conductive and evaporative losses will be reduced if the water is manually removed from the horse’s coat. The horse should be allowed access to water throughout the cooling down process; if the horse has been exercising and sweating heavily, offer electrolyte supplementation via a separate water bucket as well.
For more content like this, check out the latest issue of The Cooperator.
Animals’ bodies function best within a very narrow temperature range. Thermoregulation is the process by which the body maintains optimum core temperature (99-101°F for adult horses). Heat is produced as a result of many biological functions, including muscle contraction and metabolism. Excess heat must be transferred from the horse to its environment to maintain body temperature. Heat is transferred from one object to another by four primary mechanisms: conduction, convection, radiation, and evaporation. Conduction occurs when heat is transferred from a warmer object to a cooler object through direct contact; for example, when you touch a hot stove, heat from the stove is transferred to your hand.
Convection occurs when heat is transferred through a liquid or gas, such as the loss of body heat to the atmosphere in cold weather; air movement, via wind or fans, increases the rate of convective heat loss. Radiation is the transfer of heat from one object to another without direct contact; we can feel this effect when we step outside on a bright, sunny day. Evaporation occurs when heat transforms a liquid into to a gas; sweating and panting are both examples of evaporative heat loss mechanisms in animals. Horses produce copious amounts of sweat, especially during exercise, as an effective means of reducing their body temperature.
If horses are less tolerant than humans, does that mean we shouldn’t ride our horses during the summer? Of course not! However, you should be mindful of the extra stresses horses are under during hot, humid weather so that you can make sure your horse stays as comfortable as possible. A simple measurement of comfort in hot weather is the heat index system. A heat index is calculated by adding the air temperature (in °F) and the relative humidity (in %). The heat index is similar to a wind chill factor in winter weather; it gives us information about how comfortable – or not! – outdoor conditions are likely to be. While there are no hard and fast rules about heat index values and equine comfort, there are some generally accepted guidelines that are useful for horse owners.
When caring for very hot horses, the primary goal is to reduce their body temperature as quickly as possible. The best way to do this is by repeatedly applying cold water to the horse, ideally while either walking the horse or standing it in front of a fan. This technique maximizes multiple cooling mechanisms: conduction (cold water absorbs heat from the horse’s skin), convection (moving air allows more heat loss from the horse than still air), and evaporation.
Scraping the excess water from the horse between water applications is not necessary and will actually slow the rate of heat loss, as both conductive and evaporative losses will be reduced if the water is manually removed from the horse’s coat. The horse should be allowed access to water throughout the cooling down process; if the horse has been exercising and sweating heavily, offer electrolyte supplementation via a separate water bucket as well.
For more content like this, check out the latest issue of The Cooperator.