70 DISEASES OF THE HORSE. 



deep-seated, and in the vicinity of a joint, as the poll 

 and shoulder. The reason of this is easy of explanation, 

 for when these parts get injured, and suppurative action 

 is set up, the pus, instead of pointing to the outward sur- 

 face, burrows down in among the loose textures, and 

 forms sinuses or pipes, pointing in several directions. 

 Fistula differs from a simple abscess only in this particu- 

 lar, and the difficulty of cure. The pus secreted is nearly 

 the same. The pus in a simple abscess is secreted from, 

 and a liquification of the surrounding tissue and the pus 

 of fistula is secreted from the walls of a fibrous sack, 

 which is formed in most cases of fistula. The fistula 

 may be open or whole, presenting a large swelling. 



Symptoms. — Pain on pressure to the parts aifected, 

 followed by heat, pain, and swelling, circumscribed in 

 shape, hard at first, and becoming soft and fluctuating 

 upon pressure by the finger, and sure indication of fluid 

 within. This swelling, from the firmness and integrity 

 of the sack and skin in which it is enclosed, does not 

 break, nor yet form sinuses which take on the character 

 of an encysted tumor, which does not break of its own 

 accord, as simple abscesses do. At other times, the fis- 

 tulous tumor breaks or opens in several places, and small 

 holes discharge pus, some to-day and none to-morrow. 

 The day the discharge is free, the pain and swelling is 

 less. Among the pus will be observed organized matter 

 like cheese, or in other words, it is not uniform in thick- 

 ness or appearance. This is a disease which rarely ever 

 gets well of its own eff"orts. This arises from the nature 

 of the sore having a sack, which is only removed by art. 

 Also, from the situation of fistula presenting no depend- 

 ing opening for the outlet of the pus. 



Causes. — Bruises, accidents, caries of the bones, (which 



