SYMPTOMS 59 



out the neck may prove puzzling in the absence 

 of any pathognomic symptom. 



Then again we must differentiate (before 

 suppuration unmasks the character of the ail- 

 ment) fistula from other enlargements and 

 growths in the region. Sarcomata and melan- 

 osis may localize on the withers, and unless 

 taken into account there is some danger of 

 error in diagnosis. The former is, however, 

 rare and the latter is seen only in white horses. 

 A black work horse, submitted to the writer by 

 Dr. D. JNI. Campbell, exhibiting a voluminous 

 enlargement of the withers that had every re- 

 semblance of the fibrosis of fistula, w^as found 

 after an unsuccessful operation to be affected 

 with a very large, deeply rooted sarcoma ex- 

 tending downward into the thorax and affect- 

 ing nearly the whole of one lung in addition to 

 involving all of the structures about the 

 withers. And again, the author once submitted 

 a twelve-year-old horse, just turning white, to 

 an operation for fistula only to find that the 

 bulging was due to a melanotic tumor the size 

 of a cocoanut, located in the splenius. 



It is also important to judge carefidly recent 

 swellings of the base of the neck and of the 

 withers, as these might be mistaken for fistula. 

 Horses frequently sustain severe contusions in 

 this region, exhibiting either fluctuant or firm 



