PATHOGENESIS 41 



liniments and blisters applied to them often 

 are credited with curative properties when, in 

 fact, it was an inherent influence that operated 

 to that end. 



The duration of this stage has been very 

 difficult for us to determine. We believe, how- 

 ever, that it is very irregular, that some cases 

 develop very rapidly into clinical cases while 

 others remain almost dormant for months, 

 some disappearing entirely and some bulging 

 slowly toward the surface. 



It is these slowly forming ones that develop 

 so much fibrous tissue and thus change the en- 

 tire aspect of the condition from cyst to neo- 

 plasm. This occurrence seems almost sufficient 

 reason to include in the classification a third 

 form of fistula of the withers — the fibrous 

 form — if the reader were not familiar with the 

 remarkable aptitude of horse-flesh to form 

 fibrous tissue from continued irritation. 

 Edema, pressure, foreign body, feebly virulent 

 infection, cold abscess, granuloma and other 

 tumors in the flesh of horses cause the forma- 

 tion of great volumes of fibrous tissue luilike 

 that of any other animal. It is thus that a 

 slowly forming fistula beginning in the depths 

 of the neck becomes the underlying cause of 

 the formation of new tissue in such abundance 



