258 DISEASES OF THE SKIN 



Treatment. — Treatment is usually of little avail, and con- 

 sists in the application of local anesthetics or irritants. 



TRICHORRHEXIS NODOSA. 



Definition. — This is a condition of the hair in which nodules 

 occur along the shaft, causing the hair to bend and break off. 



It may affect the hairs of the body or the mane and tail of 

 the horse. As it sometimes occurs enzootically it is probably 

 due to an infection of the hair. It may be transmitted from 

 one animal to another or to man. 



Prognosis. — The prognosis is unfavorable. 



Treatment. — The treatment consists in the application of 

 antiseptics, such as bichlorid of mercury (1 per cent.), 

 creolin (2 per cent.), pyrogallol (1 per cent.), or pyoctanin 

 (1 per cent.). 



ACNE. 



Definition. — By acne is meant a purulent inflammation of 

 the hair follicles. There form on the skin, papules and pus- 

 tules. It is due to an infection with pus cocci and the result- 

 ing decomposition of the sebum. A parasitic form which is 

 rare in large animals is due to the mite Demodex folliculorum. 



In horses acne usually occurs in the saddle or harness 

 rests where firm, painful nodules or nodes appear out of which 

 may be expressed in the form of yellow waxy cylinders an 

 exudate which is a mixture of sebum and pus. 



Treatment. — The treatment is surgical, and consists in open- 

 ing, expressing the exudate, and curetting out the cavity, 

 which is later cauterized. 



PEMPHIGUS. 



Definition. — By pemphigus is understood a skin eruption 

 characterized by isolated vesicles, which may attain the size 

 of a hen's egg or even larger, between which the skin appears 

 intact. 



Etiology. — The causes are not known. 



Prognosis. — In animals the prognosis is good, most cases 

 healing in about two weeks. 



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