374 PRINCIPLES OF VETERINARY SURGERY 



aliculate abscesses. Their tract is covered with a velvety 

 membrane having the appearance of a mucous membrane, 

 having a base of thick fibrous tissue. The surface of this 

 pseudo-mucous membrane is constituted of proud flesh, 

 which tends to become covered with an epidermic layer in 

 the region of the orifice. The tracts which close up, cause a 

 chronic inflammation in the surrounding tissues. The con- 

 nective tissue is oedematous and becomes thick and sclerotic, 

 the vessels obliterate and the muscles degenerate, giving to 

 the fistula the quality of piercing through a fibrous mass 

 that obstructs cicatrization. 



DIAGNOSIS. — Fistute may be readily recognized from 

 the preceding symptoms. The discovery of an orifice that 

 will admit a probe to a considerable depth, together with 

 the continuous flow of a purulent product or liquid secre- 

 tion, is sufficient evidence upon which to base a diagnosis. 

 Injections with a liquid will determine whether the fistula is 

 blind or complete, and will furnish more or less accurate in- 

 formation as to the capacity and extent of the tracts. And 

 finally, an acute and persistent pain in a region where a sore 

 of small dimensions is situated, e. g. in the digital region of 

 the horse testifies as to the existence of fistula. 



PROGNOSIS. — The gravity of the disease varies accord- 

 ing to the nature of the fistula. Secreting or excreting fis- 

 tula are always more serious than those -which result from 

 the non-cicatrization of an abscess. Their seriousness is also 

 subordinate to the anatomical constitution of the region they 

 traverse, and the nature of the lesion that perpetuates the 

 suppuration. Every veterinarian is familiar with the gravity 

 of fistula of the poll, of the withers and of the region of the 

 lateral cartilages. 



TREATMENT. — Having stated above that fistulae are 

 nothing more than canaliculate ulcers, it is evident that their 

 therapeutics must have some analogies with that of ulcers. 



