324 SKIN, COLOUR, AND HAIR. 



in thorough-breds ; circulation in the former being slower 

 than in the latter. Also, the greater amount of fast work 

 which a horse does, within healthy limits, the finer is 

 his coat. Consequently, profuseness of hair should not 

 be regarded as an indication of vigour. 



A curly condition of the hair depends on the hairs 

 being more or less flat ; not round, as in straight hair. 



Skin.— The chief functions of the horse's skin, as 

 far as we are at present concerned, are : (i) to regulate 

 the temperature of the body ; (2) to aid in removing waste 

 matters from the blood ; and (3) to protect the body. As 

 the first and second duties are intimately connected wdth 

 each other, we may consider them conjointly. 



The internal temperature being maintained by the 

 changes which take place in the tissues ; exercise, by 

 promoting these changes, increases the production of heat. 

 But as it also determines blood to the surface of the body, 

 and thereby stimulates the sweat glands ; the surplus heat 

 is removed by an increased amount of evaporation from 

 the skin, which performs this work, and also that of radiating 

 heat, best when it is thin. Although the subject of health 

 is outside the scope of this book, I may remark in passing, 

 that a soft and pliable condition of the skin is due to the 

 fact of the oil glands, w^hich are imbedded in it, being in 

 good order. Granting the employment of clothing when 

 necessary, we may assume that the skin of hard-worked 

 horses, especially those which are engaged at fast paces, 

 should, within reasonable limits, be as thin as possible, 

 consistent with its being able to stand the friction and 

 pressure of harness or saddle-gear. 



Colour. — The colours of animals are either pigmental 

 or structural. Thus, the dark colour of a black horse is 

 due to black pigment ; and the red colour of a chestnut 

 horse, to red pigment. These two pigments are mixed 

 in varying proportions in bay and brown horses. The 



