MOUNTED INSTRUCTION 21 



There are numerous isolated glands, opening directly on the sur- 

 face of Ihe skin, producing- a somewhat thicker and more odorous 

 secretion. They are found in large numbers in the folds of the skin, 

 where chafing- would be liable if the surface were dry, as on the sheath, 

 scrotum, and inner side of the thigh, around the anus, in the hollow 

 of the heel, beneath the fine horn of the frog, on the inner side of the 

 elbow, on the lips, nostrils and e3^elids. When closed by dried secre- 

 tion these glands may become distended so as to form various sized 

 swellings on the skin, and when inflamed they may throw out offen- 

 sive liquid discharges, as in "grease," or produce red, tender, fungous 

 growths, commonly called "grapes." 



The cutaneous covering presents such an extensive surface for the 

 secretion of dermis scales, hairs, horn, 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 

 dififerent points of the skin v/ith 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 

 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 

 inflamm.ations of internal organs, and inflammation of such organs 

 cause in their turn eruptions of 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 ini diet, to an 

 injudicious use of cold water when the system is heated, to indiges- 

 tion and improper grooming. 



The sweat glands of the horse, like those of man, are composed of 

 simple tubes which extend down through the cuticle and dermis in a 

 spiral manner, and are coiled into balls in the deeper layer of the true 

 skin. In addition to their importance in throwing offensive waste 

 products out of the system, these tend to cool the skin and the entire 

 anatomy of the animal through the evaporation of their watery secre- 

 tion. Their activity is 'therefore a matter of no small moment, as 

 besides regulating the animal heat and excreting impurities, they 

 influence largely the internal organs through the intimate sympathy 

 maintained between them and the skin. 



Chafing is a common cause of disease of the skin and is especially 

 liable to affect the fat horse between the thighs, by the side of the 

 sheath or scrotum, on the inner side of the elbow, or where the harness 

 chafes on the poll, shoulder, back, breastbone and under the tail. The 

 accumulation of sweat and dust between the folds of the skin and on 

 the surface of the harness, and the specially acrid character of the 

 sweat, in certain horses contributes to chafing. The heels often 

 become congested owing to the irritation caused by the short bristly 

 hairs in clipped heels. Again congestion may occur from friction by 



