DISEASES OF THE SKIN. 
By James Law, F. R. C. Y.S., 
Formerly Professor of Veterinary Science, etc., Cornell University. 
As we find them described in systematic works, the diseases of the 
skin are very numerous and complex, which 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 diseased 
processes are easily seen and distinguished from one another. 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 the 
skin—the mucous membrane, which lines the air passages, the diges- 
tive organs, the urinary and generative apparatus. Diseased proc- 
esses, therefore, which in these organs it might be difficult or impos- 
sible to distinguish from one another, 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 cuticular scales, 
hairs, horn, sebaceous matter, sweat, and other excretory matters, that 
any extensive disorder in its functions may lead to serious internal 
disease and death. Again, the intimate nervous sympathy of differ- 
ent points of the skin with particular internal organs renders certain 
_skin disorders causative of internal disease and certain internal dis- 
eases causative of affections of the skin. The mere painting of the 
skin with an impermeable coating of glue is speedily fatal; a cold 
draft 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 inflammation of such organs 
cause in their turn eruptions on the skin. The relations—nervous, 
secretory, and absorptive—between the skin and internal organs 
are most extensive and varied, and therefore a visible disorder in 
the skin may point at once and specifically to a particular fault in 
diet, to an injudicious use of cold water when the system is heated, to 
a fault in drainage, ventilation, or lighting of the stables, to indiges- 
tion, to liver disease, to urinary disorder, etc. 
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