130 THE HORSE IN HEALTH AND DISEASE 



openings for the liairs and the ducts of the sebaceous and sweat- 

 glands, which he in the lower layers of the dermis. 



In health the skin feels pliable and elastic, and is easily movable 

 upon its underlying tissues. When a fold is drawn up between the 

 fingers, it quickly regains its normal position when released. 



The sebaceous glands have small openings into the hair 

 follicles. They secrete an oily substance known as sebum, which 

 serves to keep the hair glossy and the skin soft and flexible. 



The sweat- or sudoriparous glands discharge sweat directly 

 upon the surface of the skin. Sweat is a watery, sherry-colored 

 fluid, salty to the taste, of strong alkaline reaction, and charac- 

 teristic horse-like odor. Besides water it contains inorganic salts, 

 fatty acids, and waste products. It serves to keep the skin moist 

 and in good condition, to remove waste and poisonous or irritating 

 matters, and to regulate the body temperature by evaporation. 



Appendages of the skin comprise the hairs, the chestnuts and 

 ergots on the legs, and the hoofs of the feet. 



The hairs are a modification of the epithelium. Each hair has 

 a bulbous root springing from the hair-follicle, an involution in the 

 skin, into which one or two sebaceous glands empty. Involuntary 

 muscle-fibers are found at the base of the hairs, which cause them to 

 rise or "stand on end" under the influence of cold. Hair grows 

 by constant additions from the skin to which it is firmly attached. 

 The growth is regulated by the environment of the horse. The 

 hair coat is changed twice a year, once for a heavy and once for a 

 light coat. Proper food and care hasten the shedding of the hair; 

 opposite conditions tend to postpone it. Hair corresponds in 

 color to the pigment in the skin which it covers. As the animal 

 grows old there is a tendency for the hair to turn gray, especially 

 about the head. The color of the hair which comes in over a 

 wound is often white. The foal is generally quite different to its 

 color at maturity. 



Horsemen Hke to see a glossy coat and fine, short hair, as these 

 are indications of good condition, which means ability to utilize 

 feed to the best advantage. A coarse hair denotes a coarse skin. 

 Horses running at pasture show a long, lusterless, rough coat from 

 lack of grooming. The long hair on the legs of draft horses is 

 termed "the feather." When "silky" it is a sign of good quality 

 in both the skin and bone. 



The chestnuts and ergots are callus-like, horny, growths. The 



