10 INTRODUCTION 
poll-evil we have found to be much greater in 
some localities than others. In some districts 
it is actually an equine scourge, while in others 
it is arare occurrence. In southern California, 
for example, veterinarians seldom if ever see 
atypical fistula of the withers or poll-evil, while 
in central Illinois it is a veritable horse plague. 
In a recent conversation with an old horse 
breeder in the latter location the information 
was elicited that fistula was once as rare there 
as in California. Asked if he had any theory 
to advance as to the cause he seemed inclined to 
attribute most cases to influenza, and colt dis- 
temper, claiming that before these diseases be- 
came prevalent from the interchange of horses 
from shipping centers there were no cases of 
fistula of the withers. The rarity of shipping 
fever (influenza) in California, seems to add 
logic to these observations. 
But no matter what the cause may eventu- 
ally prove to be, the veterinary practitioner is 
today confronted with a serious disease of 
horses that he must endeavor to control and 
handle to the better satisfaction of horse breed- 
ers and the public. To fall short of meeting 
this requirement is one more adverse reflection 
on our ability to meet the demands of our 
growing live stock industry. To study, to ex- 
periment with, to strive to curb, and to analyze 
