We have all seen riders at our farms, competitions or even ourselves working sweaty horses. The temperature may be hot, the workload might be intense, or even a combination of the two. As many riders know, horses can even work up a lather if he or she is asked to do something unpleasant or mentally demanding (such as keeping an OTTB at a walk on a hack!)
Riders should know that there are two different types of sweat that horses produce: clear, runny sweat (like humans produce) or the thick, foamy white sweat. The clear type is healthy, it indicates the horse’s body is effectively cooling itself. This sweat contains naturally-occurring salts that regulate a variety of body processes such as those found in the heart and kidneys. When a horse has clear sweat means the horse is being worked correctly.
The white, foamy sweat that is also seen is a by-product of over-strenuous work or being exercised in excessive heat. White sweat contains proteins, which takes too long to dissipate to make an effective method of thermoregulation. While a small amount of white sweat can be present between the hind legs, on the neck by the reins or any other place where friction may occur, excessive white foam is a sign the horse is being over-worked.
To avoid over-working your horse in excessive heat, try to ride before or after the hottest parts of the day. Examine your local weather report to plan any lessons or strenuous riders during the coolest part of the week. Be prepared to spend more time after the ride to cool your horse off, which may include bathing or sponging with water, handwalking/grazing and monitoring your horse until his or her heart rate is back to normal. Talk to your vet and trainer about supplements such as electrolytes or a modified training routine to prevent excessive dehydration.