382 PERICARDITIS. 



pericarditis actually exists, i.^'., until the disease has arrived at the third 

 stage of development mentioned above. 



As long as the symptoms point only to the first or second stage, the 

 logical diagnosis is reticulitis produced by a foreign body. At this time 

 the development of pericarditis, although possible, is not inevitable. 



When, on the other hand, one knows how the digestive disturbance 

 has originated and developed and thereafter notes signs of cardiac irrita- 

 tion, disappearance of the cardiac impulse, dulness of the heart sounds, 

 venous stasis, etc., the diagnosis is easy even thus early. 



Mistakes are not very likely. Only in some cases are they liable to 

 occur, as in acute peripneumonia of the anterior pulmonary lobes, 

 causing compression of the pericardium of the anterior vena cava and 

 producing secondarily venous stasis and tedema of the dewlap. Cases 

 of specific pericarditis due to peripneumonia also occur, and under such 

 circumstances a mistake would be even more excusable. Nevertheless, 

 the temperature curve in itself is a sure indication, for whilst in peri- 

 pneumonia the fever is always very marked, it is scarcely noticeable in 

 pericarditis due to a foreign body. 



When the diagnosis of pericarditis has been arrived at it is desirable 

 to determine the exact nature of the disease, for whilst cases of peri- 

 carditis due to foreign bodies are incurable and in the interest of the 

 owner the animals should be slaughtered, pericarditis due to cold or 

 rheumatism may be successfully treated. Eheumatism generally affects 

 the synovial membranes even before it produces pericarditis, and this 

 indication, sujDplemented l)y the history of the case usually ensures one 

 against mistakes regarding the initial cause. 



It is much more difficult to distinguish pericarditis due to a 

 foreign body from pericarditis due to carcinoma and from the forms 

 of pseudo-pericarditis produced by lesions in the neighbourhood of the 

 heart. When considering the latter we shall deal with this particular 

 point. 



Prognosis. The prognosis is always fatal. 



Lesions. When the foreign body is very thin and sharp, the reti- 

 culum may not become attached to the diaphragm. In such cases its 

 passage has been rapid and the tissues have healed. 



Usually the reticulum, diaphragm and pericardium are united by a 

 mass of fibrous tissue as thick as a man's arm. It resembles a fibrous 

 sleeve surrounded by an oedematus zone, usually of slight extent. This 

 mass of new filn'ous tissue is traversed by a sinuous tract resulting from 

 the irritant action of the foreign body on the surrounding tissues. All 

 writers describe this fibrous sleeve, which, however, only occurs in cases 

 where a very long foreign body has occupied a considerable time in pass- 

 ing from the reticulum to the cavity of the chest. 



