478 DISEASES OF THE HORSE. 



Causes. — Fistulas follow as a result of abscesses, bruises, wounds, 

 or long-continued irritation by the harness. Among the more com- 

 mon causes of fistula of the poll (poll evil) are chafing by the halter 

 or heavy bridle; blows from the butt end of the whip; the horse 

 striking his head against the hayrack, beams of the ceiling, low doors, 

 etc. Fistulous withers are seen mostly in those horses that have 

 thick necks as well as those that are very high in the withers; or, 

 among saddle horses, those that are very low on the withers, the 

 saddle here riding forward and bruising the parts. They are often 

 caused by bad-fitting collars or saddles, by direct injuries from blows, 

 and from the horse rolling upon rough or sharp stones. In either 

 of these locations ulcers of the skin, or simple abscesses, if not prop- 

 erly and punctually treated, may become fistulas. The pus burrows 

 and finds lodgment deep down between the muscles, and escapes only 

 when the sinus becomes surcharged or when, during motion of the 

 parts, the matter is forced to the surface. 



SyTnptoins. — These, of course, will vary according to the progress 

 made by the fistula. Following an injury we may often notice sore- 

 ness or stiffness of the front legs, and upon careful examination of 

 the withers we will see small tortuous lines running from the point of 

 irritation downward and backward over the region of the shoulder. 

 These are superficial lymphatics, and are swollen and painful to the 

 touch. In a day or two a swelling is noticed on one or both sides of 

 the dorsal vertebrge, which is hot and painful and rapidly enlarging. 

 The stiffness of the limbs may disappear at this time, and the heat 

 and soreness of the parts may become less noticeable, but the swelling 

 remains and continues to enlarge. 



A fistulous ulcer of the poll may be first indicated by the opposition 

 which the animal offers to the application of stable brush or bridle. 

 At this time the parts are so sore and sensitive that there is some 

 danger that the patient will acquire disagreeable stable habits unless 

 handled with the greatest care. The disease in its early stages may be 

 recognized as a soft, fluctuating tumor surrounded by inflammatory 

 swelling, with the presence of enlarged lymphatic vessels and stiffness 

 of the neck. Later the inflammation of the surrounding tissues may 

 disappear, leaving a prominent tumor. The swelling, whether situ- 

 ated upon the head or the withers, may open and form a running 

 ulcer, or its contents may dry up and leave a tumor which gradually 

 develops the common characteristics of a fibrous tumor. When the 

 enlargement has opened we should carefully examine its cavity, as 

 upon its condition will wholly depend our treatment. 



Treatment. — In the earliest stage, when there is soreness, enlarged 

 lymphatics, but no well-marked swelling, the trouble may frequently 

 be aborted. To do this requires both general and local treatment. 

 A physic should be given, and the horse receive 1 ounce of powdered 



