784 DISEASES OF THE POLL. 



cal interference. Whenever the presence of the pus is established 

 the abscess must be opened, and opened very freely. This must 

 be cai'efully done. The puncture must be made in the center of 

 the tumor, and after the evacuation of the pus it njust be ex- 

 tended with the bistotu-y, introduced with the aid of a grooved 

 director, and making, of course, a counter-opening at the most 

 dependent point. This incision should be made parallel with the 

 cervical ligament, and must be carefully made, in order to avoid 

 wounding the capsular ligament of the joint, or the occipito-mus- 

 cular artery. 



The hemorrhage which accompanies this operation is easily 

 controlled by pressure. Antiseptic dressings, with the use of a 

 drainage tube constitute the after-treatment, which must be simUar 

 to that of the same diseases at the neck and at the withers, with 

 the difference, perhajas, that the dressings and cleanings must be 

 oftener renewed. 



If no complications arise the wound will heal without diffi- 

 culty, and the animal may be able to resume work after two or 

 three weeks' recuperation. 



Poll Evil. 



But if, on the contrary, the animal is suffering with the per- 

 sistent and tenacious lesion which consists in the necrosis of the 

 yellow or white fibrous tissue of the region, or a diseased condi- 

 tion of the surrounding bones, we are confronted with the very 

 serious affection commonly known as poll evil. 



This disease originates, ordinaiily, in one of those already con- 

 sidered, and yet it may appear sj)ontaneously, if the instigating 

 traumatism from which it grew has been sufficiently severe or 

 violent. And, again, it may be a sequelae or extension of a similar 

 diseased process in the neck. 



Its characteristic appearance is that of a large induration, de- 

 veloped around one or several fistulous tracts, from which escapes 

 a thin, sanious pus, of foetid odor. Upon being explored these 

 fistulas are found to vary in their direction, in their depth, and in 

 the tissue on which they tenninate. Exploring with the probe, 

 or, more certain, with the finger, a cavity is found more or less 

 filled with pus, with granulating walls, in the bottom of which 

 the cervical ligament is felt, isolated, roughened and more or less 

 escharrified, or, if this chord has remained intact, it will indicate 



