2-12 DISEASES OF THE HORSE. 



CHAP. XLIV. 



THE STRUCTURE AND DISEASES OF THE SKIN. 



[Before we proceed to its diseases, it will be proper to notice 

 briefly the structure of the skin. It is composed of three sepa- 

 rate portions. The outer, called the cuticle, is thin, transparent, 

 and insensible, and when removed is quickly restored again. 

 The next portion, immediately under the skin, is the rete- 

 mucosum, being a sort of network secreting a pigment, on the 

 colour of which depends that of the skin. The internal coat is 

 the cutis or true skin ; it is considerably thicker than the other 

 coats, though its thickness varies at different parts, being thinner 

 on the inside of the limbs and about the mouth and nostrils. It 

 possesses great sensibility, and is largely supplied with nerves. 

 It is porous in its structure, enabling the perspiration to pass out 

 fi'eely ; and it has, by the same means, a power of absorption, 

 and is well supplied with absorbents as well as other vessels. It 

 not only possesses in itself a high degree of feeling, but also in- 

 timately sympathises with other parts, and particularly with the 

 stomach. Its sensibility is much greater than the parts under- 

 neath, so that it is enabled to guard them from danger. It 

 gives support to the roots of tlie hairs, Avhich are found towards 

 its internal surface ; thus if the hairs are plucked out they are 

 soon reproduced, but if the cutis is destroyed the roots of the 

 hairs are so likewise, and the hair does not again appear, as the 

 new skin is incapable of producing it. The growth of new skin 

 is exceedingly tedious, as it only grows from the edges of the 

 old. It is, however, greatly assisted by the great extensibility 

 possessed by the old skin, which is thus enabled, in some mea- 

 sure, to cover the wound. — Ed.] 



Surfeit. 



This is a disorder of the skin, consisting of small tumours or 

 pimples all over the body, which become small scabs, and then 

 gradually get well, while fi*esh ones continue to break out and 

 pursue the same course. The horse has generally a dry un- 

 healthy coat, and is hide-bound; sometimes there is swelling 

 of the hind legs likewise, and general debility. This disorder 

 is commonly produced by unwholesome feeding and general ill 

 treatment. 



[In other cases the affection appears in horses full of flesh, in 

 whom it is usually manifested in the spring or early summer 

 montiis, and is caused by plethora or a redundancy of blood, 

 which, at this season of the year, is most likely to occur. Some- 

 times it is caused by a draught of cold water in liot weather. 



