EXUDATIVE PERICARDITIS DUE TO FOREIGN BODIES. 377 



method of feeding results in bolting the food almost without mastication, 

 hence the possibility of swallowing foreign bodies. 



The proximity of the reticulum to the pericardium is also an impor- 

 tant factor, because the foreign bodies fall into the reticulum as soon 

 as the bolus of food begins to break up. It is important to notice, 

 moreover, that pericarditis is commonest on farms where the oxen are 

 attended by women, or in regions where sharp objects are to be found on 

 roads or pastures frequented by the animals, such as the vicinity of 

 needle, nail, and rivet factories. 



The sole cause is the penetration of a foreign body into the peri- 

 cardial sac. 



Pathogeny. All kinds of foreign bodies are swallowed by oxen, as 

 is abundantly shown by post-mortem examinations. These indigestible 

 bodies pass with the food into the rumen, and accumulate in the deepest 

 portions of that receptacle. Owing to physiological contractions the 

 lower wall of the rumen rises to the level of the orifice of communication 

 with the reticulum, and so passes much of the material accumulated 

 within it into this organ. 



Soft foreign bodies fall towards the lower parts of the reticulum, but 

 sharp objects may lodge in its walls. Very often the bodies penetrate in 

 this way without causing reticulitis or grave inflammation. The func- 

 tions of the reticulum are not impeded. The commonest of such objects 

 are needles, pins, nails, or fragments of iron wire. On account of their 

 form, needles are the most dangerous. The sharpness of one extremity 

 ensures its passing readily through the tissues, and as the point is 

 the part that offers least resistance, the needle continues gradually to 



penetrate. 



If the foreign body becomes implanted vertically in the lower wall of 

 the rumen or reticulum it may be expelled directly through the medium 

 of an abscess. This is a favourable termination, though it usually 

 results in permanent gastric fistula. 



More often the objects penetrate the anterior wall of the reticulum 

 and gradually work their way towards the diaphragm, impelled l)y the 

 movements of the reticulum and the other digestive compartments. 

 They perforate the muscle and pass into the thoracic cavity, either in 

 the direction of the pericardium or of the pleural sacs. 



First as to the penetration of the pericardmm. The foreign body, 

 whatever it may be, produces by its presence alone very marked irrita- 

 tion and as in addition it is always infected in consequence of its having 

 passed through the digestive compartments, inflammation is set up to a 

 degree proportionate to the pathogenic qualities of the infective agent. 



Symptoms. The early symptoms are those of indigestion, and not of 

 pericardial disease, a fact which is easy to understand, because at first the 



