178 PRINCIPLES OF VETERINARY SCIENCE 



of the body except the muzzle, lips, teats, and genitals. It 

 prevents rapid radiation and conduction of heat. 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 and excitement. Hair grows by constant additions from 

 the skin to which it is firmly attached. The growth is regulated 

 by the breed and care of the animal. The hair coat of the horse 

 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 generally 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 in 

 color to what it will be at maturity. On account of their color, 

 gray horses seem better able to withstand heat than black. 



Horsemen like 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. Coarse hair denotes 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 the callus-like, horny growths 

 seen on horses' legs. The former are usually regarded as vestiges 

 of the first digit. They are of variable form and size and occur 

 on the inner surface of the forearm, and on the lower part of the 

 inner face of the hock. The ergot is a small mass of horn which 

 is situated in the tuft of hair at the fetlock. It is the vestige of 

 the second and fourth digits and hence is absent in cases in 

 which these digits are developed. 



Horn is skin that has undergone a modification. It consists 

 of tubes of minute size held together by a cementing substance. 



THE FOOT 



The foot of the horse is a most important structure (Fig. 57) . 

 The utility of the animal may be largely measured by the fitness 



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