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 is an irritation of the skin which occurs among colts and young horses, generally in spring or early summer months; but may appear at any season of the year. It has been attribut ed by some to change of weather and by others to something in the diet; the exact cause, however, is unknown. It comes on very suddenly. An animal all right in the morning may be covered with little nodules at noon. The nodules are broad at the base and rise up from a quarter to a half inch high, resembling a swelling from a bee sting. They may be only on some part of the body or may cover head and neck as well, and sometimes the eyes are closed with the swellings. It is not serious, and often passes off as suddenly as it came on.
Treatment. - Bathe the swellings with salt water and give a heaping teaspoonful of nitrate of potash three times a day, or a tablespoonful of Epsom salt twice a day till the skin is all clear again.