This section is from the book "The Farmers Ready Reference Or Hand Book Of Diseases Of Horses And Cattle", by S. C. Orr. . Also available from Amazon: The Farmer's Ready Reference;.
This occurs occasionally when in a low-lying field surrounded by timber, shutting off all breeze, and under a broiling-hot sun a horse is pushed beyond its powers of endurance.
Symptoms. - The horse becomes slow and dumpish; pays little heed to the driver; staggers about; the sweat suddenly dries up; the breathing becomes labored, and he finally drops down and becomes unconscious.
Treatment - If noticed before he goes down, stop in a shady place where there is a current of cool air; give a drink of cool water and let him rest an hour or two. If the horse falls apply cold water or ice to the head and along the spine, but cover the balance of the body up warm and get the perspiration started. If he can swallow give two ounces of nitre and repeat it in an hour. If he begins to revive give one ounce of aloes, then give two to four drachms of bromide of potassium three times a day for several days.