HYDROTHORAX 65 



sterilized trocar and cannula or aspirating needle. It is best 

 done with the animal in either a sitting or standing position. 

 Remove the hair from and disinfect a small area on the side 

 of the thorax so that the instrument may be inserted (in a 

 forward direction) at the anterior border of the sixth, seventh 

 and eighth ribs and as low in the cavity as possible. The 

 cavity is reached as soon as resistance to the passage of the 

 'needle has ceased. The fluid flows out in a continuous stream 

 at first, then synchronous with respiration. After some of the 

 fluid is out, the air may rush in during inspiration, and to 

 prevent this hold the finger over the tube at the end of each 

 expiration. If the flow ceases suddenly it is due to plugging 

 with flakes of fibrin which can be forced away by reinsertion 

 of the trocar. The amount of fluid removed depends upon 

 the heart action. When it becomes weak and rapid, or when 

 coughing suddenly develops, the operation should be dis- 

 continued. This can be done daily at a different site of 

 puncture until all of the fluid is removed. 



HYDROTHORAX. 



Definition.— A collection of serous fluid in the thoracic 

 cavity without inflammation of the pleura. 



Etiology.— This condition always occurs as a secondary 

 process and is a symptom of many affections (insufficiency of 

 the heart; nephritis; chronic diseases of the lungs) . It usually 

 accompanies ascites, hydropericardium and edema of the 

 skin; also due to obstruction of vessels (vena azygos) ; follows 

 a general anemia, hydremia, chronic infectious diseases, 

 carcinomas and sarcomas. These latter diseases damage 

 the endothelium of the vessels and allow the transudation 

 of fluid from them. 



Pathology.— The transudate is light or reddish-yellow in 

 color and contains a few flakes of fibrin. If the condition 

 develops very rapidly, the transudate contains many red 

 corpuscles. The specific gravity and albumin content are 

 less than that of blood serum. The pleura may be thickened 

 and pale. 

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