244 Veterinary Medicine. 



ing already referred to. Another condition is that in which false 

 membranes of considerable thickness invest a lung and, following 

 the law of all fibrous structures in process of organization, they 

 contract and cause a compression and partial collapse of the con- 

 tained lung tissue. A flattening of the corresponding side of the 

 chest and a muffled and almost inaudible respiratory murmur is 

 the result of this condition. In some measure these symptoms 

 are present during convalescence in all cases of pleurisy since the 

 lung never expands to its full size till some time after apparent re- 

 covery, but it is only when the organ is invested with false mem- 

 brane that the symptoms are very apparent. 



In all such cases of prolonged pleurisy from protracted structural 

 change there is continued illness without the violent symptoms by 

 which the acute form of the disease is manifested. The acute 

 suffering, the restlessness, the grunt, and even the catching 

 breathing may be absent ; the temperature may be almost reduced 

 to the healthy .standard, the pulse small and tolerably soft, the 

 appetite considerably improved and the different secretions toler- 

 ably normal ; yet the pinching of the intercostal spaces causes 

 sharp pain, and measurement, auscultation and percussion testify to 

 the persistence of disease. The animal is hidebound, unthrifty 

 and unequal to any exertion. The cough is weak and painful and 

 sometimes accompanied by a grunt. 



Besides the changes connected with exudation and effusion, 

 and organization or suppuration in the exuded products, gangrene 

 sometimes results. A case of this kind is related by Percivall. 



The duration of pleurisy may thus extend from two days in 

 very acute cases to several weeks, or even months if we estimate 

 it by the continuance of hydro-thorax in the chronic cases. 



Post Mortem Appearances. These consist mainly in the pres- 

 ence of false membranes lining the pleura and hanging in cobweb 

 like shreds into the cavity of the chest, and of the liquid effusion 

 which fills up the chest at its most dependent part. The pericar- 

 dium also contains fluid in many cases. The periods at which 

 exudation takes place, and when the principal changes take place 

 in the exuded materials have been well investigated by Dupuy, 

 Hamont, Delafond and St.Cyr. They induced pleurisy by inject- 

 ing irritant liquids into the chest, and noted the regular sequence 

 of changes. 



