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 inte 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. M. Campbell, exhibiting a voluminous 
enlargement of the withers that had every re- 
semblance of the fibrosis of fistula, was 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 carefully 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 
