296 HORSE, SWINE AND POULTRY DISEASES 



were dry, as on the sheath, scrotum, mammary glands, and inner 

 side of the thigh, around the anus and vulva, 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 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. 



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 offen- 

 sive 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. Dis- 

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

 most marked features, into the following classes: 



(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) inflammation 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 (bullee) ; (e) inflammation with a similar eruption, but 

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

 tion (pustules) ; (f) the formation of pustules implicating the su- 

 perficial layer of 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 sensa- 

 tions of itching, 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 con- 

 nected with a specific poison, such as horsepox, erysipelas, anthrax, 

 farcy, or cutaneous glanders, etc. (6) Physical injuries, like 

 wounds, burns, scalds, etc. 



^ CONGESTION (RED EFFLORESCENCE, OR ERYTHEMA). 



This is a congested or slightly inflamed condition of the 

 skin, unattended by any eruption. The part is slightly swollen, 

 hot, tender, or itchy, and dry, and if the skin is white there is 

 redness. The redness is effaced by pressure, but reappears instantly 

 when the pressure is removed. Unless in transient cases the hairs 

 are liable to be shed. It may be looked on as the first stage of in- 

 flammation, and therefore when it becomes aggravated it may 



