16 FISTULA AND POLL-EVIL 



without change of arrangement into the neck 

 and back. Thus pus within the withers after 

 filtering downward finds its only exit by trav- 

 eling first in either of these two directions, and 

 ultimately to the surface of the body at points 

 remote from the seat of development. It is 

 this complex arrangement that affords the im- 

 pregnable intrenchment of pathological prod- 

 ucts and that is responsible for the refractory 

 character, the extreme seriousness and the un- 

 varying chronicity of the disease known as fis- 

 tula of the withers. 



The Skin 



The skin covering the withers possesses noth- 

 ing unusual except the thickness of the subcut- 

 em along the median line anteriorly where the 

 heavy connective tissue of the mane begins. Pos- 

 terior to the summit of the withers the skin is of 

 normal thickness, but is separable only with 

 difficulty from the aponeurosis of the fleshy 

 panniculus whose fixed attachment is at the 

 level of the fourth or fifth spine. Very often, 

 however, the skin is the seat of scars superven- 

 ing harness and collar injuries which fuse it 

 into the underlying ligaments, fascia or mus- 

 cles as the location may determine. 



Panniculus Carnosis (Cutaneous Muscle) 



This muscular structure is a prominent feat- 

 ure of the withers in that its chief attachment 



