434 DISEASES OF THE HOESE. 



of the elbow, on the lips, nostrils, and eyelids. When closed by dried 

 secretion or otherwise these glands may become distended so as to 

 form various-sized swellings on the skin, and when inflamed they 

 may throw out offensive liquid discharges, as in " grease," or produce 

 red, tender fungous growths (" grapes "). 



The sweat glands of the horse, like those of mail, 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 glands tend to cool the skin and the 

 entire economy of the animal through the evaporation of their watery 

 secretion. 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. 



Diseases of the skin may be conveniently divided, according to their 

 most marked features, into — 



(1) Those in which congestion and inflammation are the most 

 marked features, varying according to the grade or form into (a) 

 congestion with simple redness, dryness, and heat, but no eruption 

 (erythema) ; (b) inflammation with red-pointed elevations, but no 

 blisters (papules) ; (c) inflamm,ation with fine conical elevations, 

 each surmounted by a minute blister (vesicle) ; (d) inflammation 

 with a similar eruption but with larger blisters, like half a pea and 

 upwards (bullce) ; (e) inflammation with a similar eruption, but 

 with a small sac of white creamy pus on the summit of each elevation 

 (pustules) ; (/) the formation of pustules implicating the superficial 

 laj^er of the true skin, a small portion of which dies and is thrown off 

 as a slough, or " core " (boils) ; (g) the formation of round, nodular, 

 transient swellings in the true skin (tubercles) ; and (h) the excessive 

 production of scales, or dandruff (scaly or squamous affections). 



(2) Diseases in which there are only deranged sensations of itch- 

 ing, heat, tenderness, etc. (neurosis). 



(3) Diseased growths, such as warts, callosities, horny growths, 

 cancer, etc. 



(4) Diseases due to parasites, animal and vegetable. 



(5) Diseases connected with a specific poison, such as horsepox, 

 erysipelas, anthrax, farcy, or cutaneous glanders, etc. 



(6) Physical injuries, like wounds, burns, scalds, etc. 



CONGESTION (eeD EPPLOEESCENCE, OE EEYTHEMa) . 



This is a congested or slightly inflamed condition of the skin, unat- 

 tended by any eruption. The part is slightly swollen, hot, tender, 

 or itchy, and dry, and if the skin is white there is redness. The red- 



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