CHAPTER I . 



DISEASES OF THE SKIN 



General ronarks on the functions of the Skin. Mange. Dermatodectes Equi. 

 Sarcoptes Equi. Synibiotes Equi. Ringworm. Urticaria^ or Surfeit. 

 Hide-bound. Eczema. Cracked Heels. Grease and Grapes. Mai lenders 

 and Sallenders. Mud Fever. Warts. 



GENERAL REMARKS ON THE FUNCTIONS OF THE SKIN. 



As the diseases of the skin of the horse are very numerous and varied,. it is 

 our purpose to enter pretty fuHy into the consideration of their symptoms 

 and treatment. Before, however, commencing our description, we may say 

 a few words regarding the functions and structural peculiarities of this 

 important covering, for these are of interest and are well worthy of a few 

 moments careful attention. 



The skin is described as a soft and pliant membrane, which in^•ests the 

 whole of the external surface of the body, following its prominences, its 

 depressions, and its curves. It serves as an effectual protecting cover, 

 preventing the penetration of noxious materials, and allowing of the escape 

 of effete matter in a gaseous liquid and solid state from the blood. The skin 

 also has other important offices, for it acts as a sensitive organ in the 

 exercise of touch ; while it plays a very important part in keeping the 

 temperature of the body constant. This varies in health in the horse from 

 ioo° to ioi° F. Our readers are aware how the blood vessels of the skin 

 become contracted in cold weather, and how, on the contrar}^, in hot 

 •weather they dilate, when perspiration is excreted in much larger quantity. 

 By the evaporation of the sweat passed out, heat is absorbed, and thus the 

 bodily temperature does not increase materially on the hottest summers day. 

 Exercise increases the production of heat in the body, but it also increases 

 the rapidity of the circulation in the blood \essels, which become dilated, 

 and thus the sweat glands of the skin become more active. By the 

 perspiration excreted and vaporised on the surface of the body, heat is 

 prevented from increasing above the standard in health. The actual 

 quantity of water excreted per day by the skin in the shape of w-atery vapour 

 is very large. In the human body it varies from a pint and a half, to two 

 pints. Finally, also, the skin acts as-an absorbing organ. 

 I 



