Most horse riders and trainers are aware that sweaty horses become the norm during strenuous workouts as summer weather approaches and the temperature increases. Riders need to be aware that some sweating is normal and healthy, but when the sweat becomes a lather of white foam, the horse's body is in the danger zone.
A thick white lather indicates that the horse is being overworked or is becoming too heated and the horse's body is saying, "Whoa!" let's not carry this workout too far."
Foamy sweat = too much heat
White, foamy sweat is a by-product of over-strenuous work or being exercised in excessive heat.
When the sweat is clear and runny, it serves notice that the horse's body is effectively cooling itself.This sweat contains naturally-occurring salts that regulate a variety of body processes including those of the heart and kidneys. When a horse has clear sweat means the horse is being worked correctly.
White, foamy sweat is a by-product of over-strenuous work or being exercised in excessive heat. White sweat contains proteins, which take too long to dissipate to make an effective method of cooling the horse's body. 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.
If a horse develops a lather of sweat on a regular basis, check with your vet and trainer about supplements such as electrolytes or a modified training routine to prevent excessive dehydration.
Read more about sweat and your horse