Your horse could be at risk for heatstroke or even death if the heat and humidity added together are too high. Heatstroke happens when the horse is producing more heat than it can dissipate. Normal temperature for a horse is between 100 and 100.5 degrees Fahrenheit. If your horse’s temperature reaches 103.5, his metabolic processes will be challenged. If his temperature reaches 105 degrees, he may show signs of incoordination or regularity in its paces and he will be irritable and sluggish. If you allow the horse’s temperature to remain over 105 degrees for more than a few minutes, the horse’s sweating will shut down and the heat will affect the horse’s brain functions. He may become disorientated. If the temperature continues to rise to 108 or beyond, the horse will likely collapse, suffer convulsions and die.
Heat production can increase by 10 to 20 times over resting values even with gentle exercise. Sprinting results in an increase of 40 to 50 times over resting values. At work levels of 150 heartbeats per minute, as in racing, a horse’s temperature will go up 1.8 degrees Fahrenheit every three minutes.
Working your horses in high humidity and high temperatures will significantly increase the horse’s susceptibility to heatstroke. High humidity does not allow the sweat to evaporate because up to two-thirds of the heat-releasing sweat will roll off of the horse’s body before it can evaporate and cool the horse. This means efficient sweating is not always synonymous with efficient cooling.
Be safe and follow the guidelines in the chart below. Click her to print out the Heat & Humidity Horse Heatstroke Chart to keep on hand.