DISEASES OF THE SKIN. 



By JAMES LAW, F. R. C. S. V. S., 



Profcscor of Veterinary Science, etc., Cornell University. 



As we find them described in systematic works, tlie diseases of the 

 skin are very numerous and complex, whicii may be largely accounted 

 for by the fact that the cutaneous covering is exposed to view at all 

 points, so that shades of difference in inflammatory and other dis- 

 eased processes are easily seen and distinguished from each other. 

 In the horse the hairy covering serves to some extent to mask the 

 symptoms, and hence the nonprofessional man is tempted to apply 

 the term "mange " to all alike, and it is only a step further to apply the 

 same treatment to all these widely different disorders. Yet even in 

 the hairy quadruped the distinction can be made in a way which 

 can not be done in disorders of that counterpart and prolongation of 

 tiie skin— tlie mucous membrane, which lines the air passages, the 

 digestive organs, the urinary and generative apparatus. Diseased 

 processes, therefore, which in these organs it might be difficult or 

 impossible to distinguish from each otlier, can usually be separated 

 and recognized when appearing in the skin. 



Nor is this differentiation unimportant. The cutaneous covering 

 presents such an extensive surface for the secretion of cuticula? 

 scales, hairs, horn, sebaceous matter, sweat, and other excretory mat- 

 ters, that any extensive disorder in its functions may lead to serious 

 internal disease and death. Again, the intimate nervous sympathy 

 of different points of the skin with particular internal organs renders 

 certain skin disorders causative of internal disease and certain inter- 

 nal diseases causative of affections of the skin. The mere painting 

 of the skin with an impermeable coating of glue is speedily fatal; a 

 cold draught striking on the chest causes inflammation of the lungs 

 or pleura; a skin eruption speedily follows certain disorders of the 

 stomach, the liver, the kidneys, or even the lungs; simple burns of 

 the skin cause inflammations of internal organs, and inflammations 

 of such organs cause in their turn eruptions on the skin. The rela- 

 tions—nervous, secretory, and absorptive— between the skin and 

 internal organs are most extensive and varied, and therefore a visible 



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