G48 sroRADic diseases. 



disease of the pleura. The symptoms of hydrothorax are short, 

 quick, laboured respiration ; the pulse small, quick, soft, often 

 intermitting; auscultation reveals absence of sound in the 

 inferior part of the chest, or a sound resembling that of drops 

 of water falling into a well, as has been already explained. The 

 hydrothorax in the horse generally invades both sides of the 

 cavity of the thorax, for a communication exists owing to the 

 loose diaphanous or web-like structure of the mediastinum, as 

 pointed out by Eigot, Delafond, and Bouley. This natural 

 communication is in some instances obliterated by exudation of 

 lymph on the mediastinal surface, in which the hydrothorax 

 will be confined to the one side. In other instances the serous 

 effusion, confined in sacs of adventitious products, will be con- 

 fined to certain circumscribed parts of the chest only. The 

 liquid effused is composed of serum mixed with flakes of lymph, 

 and is generally more or less clear upon the surface, turbid in 

 the lower parts from admixture with particles of exudative 

 materials ; it is sometimes, however, tinged with blood. If the 

 clear liquid be placed in a glass and left at rest, it generally 

 separates into clot and serum, proving that it contains tlie con- 

 stituents of fibrin, which coagulate on exposure to the atmosphere. 



In forty-three cases observed by M. St. Cyr, the effusion 

 from the first to the seventh day presented a port wine colour in 

 nine cases, a sero-sanguineous appearance in six, muddy or greyish 

 in three. From the eighth to the fifteenth day the port wine 

 colour was observed in two, the sero-sanguineous in three, muddy 

 greyish in four, and limpid in six. From the sixteenth to the 

 thirtieth day the colour was limpid in five cases, and after the 

 thirtieth it was also limpid in three cases. M. St. Cyr draws 

 the conclusion that the liquid begins to clear up towards the 

 end of the second week, and that it is clear after the twenty- 

 fifth or thirtieth day, and that this is the epoch from the acute 

 to the chronic state of pleurisy. 



English veterinarians generally maintain that the advent of 

 hydrothorax is manifested by an apparent improvement of the 

 pleuritic symptoms. They state that the pulse falls, the breath- 

 ing becomes easier, &c. This is so far true, but is not diagnostic, 

 as the abatement of the symptoms indicates the subsidence of 

 the pain and fever, and that the dry condition of the pleura has 

 passed on to that of increased effusion, its natural sequence. 



