PRINCIPLES OF VETERINARY SURGERY 371 



ward, should be combated with strong antiseptics in lotions 

 or ointments. 



The treatment of symptomatic ulcers varies according to 

 the nature of the disease upon which their existence depends, 



FISTULA. 



The word "fistula" is applied to abnormal ducts (or chan- 

 nels) either congenital or acquired. 



CLASSIFICATION.— Fistula; are divided into two 

 categories, — congenital fistulae and pathological fistulae. The 

 former, which will not be discussed in this work, have their 

 origin in an opening or embryonic cleft that fails to close. Of 

 the latter, — pathological fistulas, — there are several varie- 

 ties. They are called blind or non-communicating when 

 they terminate with a cul-de-sac in the tissues; complete or 

 communicating when they have two openings; idiopathic 

 when they follow an abscess; and symptomatic when they 

 are connected with a deep lesion. When they burst in a 

 mucous membrane they are called mucous fistulas, and if 

 they open on the skin they are cutaneous fistulte. They may 

 be mixed, cutaneous, mucous, bi-cutaneous, or bi-mucous. 

 German writers divide fistulae into two groups : 



1st. Those which discharge pus. 



2nd. Those which secrete or excrete the product of an 

 interna] organ. 



FREQUENCY. — Fistulae are of frequent occurrence in 

 the horse, the ox, the sheep, the goat, and the dog. They are 

 especially common among the horse and ox. 



ETIOLOGY. — In the domestic animals hot abscesses 

 are often the origin of fistulae, especially when their evacua- 

 tion has been delayed too long, or when the incision has not 

 been made at the most pendent point. Lesions of the poll 

 and withers of the horse, are for this reason so frequently 

 complicated with fistula. Hot abscesses in contact with a 



