With extra hours of daylight, vacation time and a variety of horse activities, summer may be the busiest season for horse owners. Like human "weekend athletes," horses can overexert and suffer the consequences, especially if the weather is extremely hot. Do what is necessary to keep your horse comfortable in hot weather.
Symptoms of heat stress are profuse sweating, rapid breathing and accelerated heart rate. Know your horse's normal heart rate, respiration and temperature. (See "Check vital signs.")
To determine the risk of heat stress, add the air temperature (degrees Fahrenheit) and the humidity, then subtract the wind speed. If your total is less than 130, your horse isn't in danger. If the number is near 150, reduce hauling and exercise, especially in high humidity. If the total exceeds 180, refrain from exercise and hauling.
When a horse loses water through perspiration faster than it can be replaced, it becomes dehydrated.
A "pinch" test can help determine if your horse is dehydrated. Pinch a small section of skin on the neck or shoulder and release. If the skin is slow to go back into place, the horse could be dehydrated.
Slow capillary refill is also an indicator of dehydration. Check this by pressing a finger against the horse's gums. When the pressure is released, the white space should return to a pink color within two to three seconds.
During hot weather, frequently offer your horse small amounts of water. But if the horse becomes too hot, limit his access to water.
A cool-down period is important after exercise. Walking the horse will increase circulation and allow it to sweat.
If you suspect heat stress, lower the horse's body temperature quickly. Get the horse into shade and hose him off with cool water.
Check vital signs
Check your horse's temperature, pulse and respiration when he is calm, cool and in good health. Put the information with his veterinary records, to be used for comparison if the horse is overheated or seems ill.
Keep a digital thermometer in your equine medical kit. Lubricate with petroleum jelly and insert the thermometer into the horse's rectum. It's a good idea to tie a string to the end of the thermometer. Many digital thermometers take readings quickly and beep when they are done. Normal temperature for a horse is 99 to 100.8 degrees Fahrenheit. Temperatures above 104F could indicate life-threatening illness.
A horse's pulse can be taken by placing ends of fingers against an artery on the lower jaw midway between the angle of the jaw and front teeth, or inside the foreleg, just in front of the elbow.
To determine the number of heartbeats per minute, count for 15 seconds and multiply by four. A normal resting horse has a heart rate of 35-40 beats per minute. A rate above 80 should be considered serious in most non-exercising horses. Heart rates that stay above 60 in a horse that is calm can be a sign of trouble.
The horse should spend equal time breathing in and breathing out. Respiration can be counted by watching the horse's nostrils, watching the horse's torso at the end of the rib cage, or by listening to the trachea (windpipe) in the neck.
As with the heart rate, count for 15 seconds and multiply by four. A normal adult horse at rest breathes eight to 20 times per minute (sources vary on exact number). High respiratory rates indicate pain, excitement, elevated temperature and/or a wide variety of possible infections.