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A MANUAL OF VETERINARY PHYSIOLOGY 



inside of the thighs, inside the cartilage of the ears, and on the 

 mammary gland and genitals. By means of the hair the heat 

 of the body is maintained and prevented from passing off too 

 rapidly. The thickness of the hairy covering varies considera- 

 bly with the class of horse ; the better bred the animal the finer 

 the coat. Draught horses yield between 3J to 3} kilogrammes 

 (7 or 8 pounds) of mixed hair, dirt, and dandruff by clipping ; 

 in a well-bred horse this would be reduced to 283 grammes 

 (10 ounces), or even less ; the amount of hair of the mane and 

 tail is about f kilogrammes (ij pounds). It is a well-known 

 fact that, excepting the hair of the mane and tail, that of every 



other part of the body has only 

 a temporary existence, and is 

 changed twice a year, once for a 

 thick, and once for a fine coat. 

 During this period horses are gene- 

 rally regarded as not being at their 

 best, and changing the coat is 

 always urged as a cause of loss of 

 condition or stamina. The perma- 

 nent hair is not entirely represented 

 by that of the mane and tail ; the 

 eyelashes and fetlock hair are per- 

 manent, also the long tactile hairs 

 on the muzzle. The temporary 

 hairs on the horse are of two 

 kinds, which can only be distin- 

 guished by their rate of growth. 

 If a part be clipped, or, preferably, 

 shaved and the growth watched, 

 in a short time it will receive a 

 scanty covering of long, rapidly 

 growing hair, followed by a slow 

 growth of ordinary hair. There 

 is no difference in the two hairs, excepting the length. The 

 long rapidly growing hairs are known as ' cat hairs '; they 

 are not numerous, being about 4 per square centimetre 

 (27 to the square inch), while the ordinary hairs are nearly 

 700 per square centimetre (4,300 to the square inch).* It 

 may yet be shown that ' cat hairs ' are tactile in function. 

 The growth of the hair is regulated by the surrounding tem- 

 perature. If horses in the depth of winter are placed in a 

 heated atmosphere, such as a horse deck on board ship, the 

 majority commence to shed their winter coat in a few days, 



* I am indebted to Major Newsom, Army Veterinary Corps, for the 

 trouble he has taken in making this tedious calculation. 



Fig. 89. — Section of Mucous Mem- 

 brane of the Horse's Lip, 

 showing the nerve endings 

 in the Touch Papilla. 



