442 OPEEATIONS ON THE DIGESTIVE APPARATUS. 



often escape discovery, notwithstanding a somewhat positive exhi- 

 bition of abdominal and thoracic symptoms. And if this is so 

 with the acute form, it must necessarily more frequently occur with 

 chronic cases, which not only do not jeopardise life, but even fail 

 to interfere with the usefulness of the animal. The horse thus 

 affected not only has the double expiration of his emphysematous 

 lungs, but he continues to be subject to intermittent colics, and 

 especially if the hernia is formed by the intestines, and they con- 

 tinue to suffer from occasional obstructions. To this complication 

 of occasional actual obstruction must be added a perpetual hability 

 to become strangulated, with a certainty of speedy death following 

 that accident. 



The lesions found at the post-mortem examinations of ani- 

 mals which have died with this description of hernia varies. The 

 accidental diaphragmatic openings may exist in different parts 

 of the central aponeurotic portion or in the peripherical muscular 

 zone, and may assume various forms, being at one time round, at 

 another eliptic or triangular, or indefinite and irregular, at times 

 very narrow, at others so extensive that the abdominal and thoracic 

 cavities are no longer distinct. Between these two extremes there 

 are many degrees and ample scope for the formation of chronic 

 hernias of a non-maUgnant character. "When the hernia is recent 

 and has existed before death, the borders of the laceration whether 

 muscular or aponeurotic, are irregular, thready, infiltrated and 

 bloody, with small blackish clots adhering to the extremities of 

 the red muscular fibres. But when the rupture is of post-mortem 

 formation, resulting from excessive meteorism, there is no trace of 

 capillary hemorrhage upon the lacerated edges of the aperture. 



With a chronic hernia these edges have various aspects; at 

 times thin, at others in thick cords ; now torn in scallops, and 

 again with a regular edge, they are always smooth, hard, of fibrous 

 consistency, and even presenting a cartilaginous aspect. There is 

 never any formation of a special serous sac for these hernias, even 

 for those which take place through the normal openings. The 

 organs most commonly met in these diaphragmatoceles are the 

 omentum, the small intestines, the anterior curvature of the large 

 colon, and more rarely, the spleen and the stomach. If not con- 

 gested by pressure in passing through the opening, they continue 

 to perform their functions. 



In these injuries the prognosis can never be confidently favor- 



