80 PRINCIPLES OF VETEBINABY SUBGEEI 



duced agent — and one certainly of great value — protargol; 

 also the actual cautery. 



What are the essential points to he observed in operating a 

 fistula ? 

 Do not simply split the fistulous canal ; it is insufficient ; 

 but remove all chronically inflamed parts and the ulcerating 

 bottom of the fistula, and provide drainage if necessary by 

 counter openings. Reasonable antisepsis is necessary to t 

 avoid infection of the operation "wounds by the previous 

 purulent focci, or an acute purulent infection — that is, acute 

 cellulitis — is likely to follow. Never operate a fistula as long 

 as an acute cellulitis involves its neighborhood — well exem- 

 plified in quittor operations ; treat this cellulitis, and then 

 operate. 



Describe the sympto^ms, common to secretory and excretory 

 fistula. 

 There is a fistulous opening and a fistulous canal, which 

 in the secretory fistula communicates with a gland, as, for 

 instance, in the salivary fistula in the horse, the parotid; 

 while in the excretory fistula the fistulous tract leads to some 

 excretory organ, as the stomach, bladder, rectum, etc. These 

 fistulae, therefore, may discharge milk, saliva, urine, faeces, 

 food, etc. 



Do secretory and excretory fistula yield readily to treatment? 

 They do not ; because the irritating nature and the con- 

 tinuous pressure of the discharge persistently interferes with, 

 the process of healing. 



Outline the treatment of secretory and excretory fistula. 



The actual cautery and other escharotics are of little 

 value. Usually the best procedure consists in changing the 



