140 JUGULAR riTLEBOTOMY. 



pressure may be relaxed and repeated once or twice, when the rising 

 and falling of the vein will render its position evident. Immediately 

 it appears clearly the plate of the fleam is adjusted just over it and 

 parallel with its long axis, the trigger is gently pressed, and the 

 incision made. The fleam is then removed, but compression of the 

 vein below the incision must be continued until the necessary quantity 

 of blood has been obtained. 



If the vein has only been stabbed, the blood flows in drops or in 

 a very thin stream. In such case operation should not be repeated 

 at the same point. Sometimes the blood at first flows in a thick 

 stream, but soon diminishes in spite of continued compression. This 

 is due to the skin having slipped to one side and covered the wound 

 in the vein, or to a fragment of subcutaneous tissue having inter- 

 posed itself. By slightly moving the skin or the horse's head, or 

 by inserting the finger in the animal's mouth and so causing it to 

 make chewing movements, the flow can be restored. Occasionally 

 the vein is opened over a valve, which falls into the wound and 

 obstructs the stream. 



Jets of bright red blood mixed with the darker stream show that 

 the carotid has been opened ; and if the wound be large the animal 

 may bleed to death, unless the carotid be immediately ligated. The 

 vessel should be firmly compressed by an assistant, the existing 

 cutaneous wound enlarged for a distance of three to four inches, 

 the subscapulo-hyoideus muscle divided, and the carotid exposed 

 by blunt dissection. The artery should be grasped with the fingers, 

 drawn forward, freed from the nerves which accompany it, and, 

 on account of the collateral circulation, doubly ligated. Care must 

 be taken in separating the recurrent and other nerves and in cleansing 

 the wound, as injury to the nerves or irritation produced by local 

 suppuration may be followed by cardiac disturbance, dyspnoea, 

 paralysis or " roaring." Other methods like continued compression 

 of the artery and closure of the skin with sutures have been recom- 

 mended. Compression might in isolated cases be followed by 

 haemostasis, but closure of the skin wound is dangerous. Experiment 

 shows that a large hematoma usually develops, and pressure on 

 the trachea may become so severe as to threaten suffocation. 



Sometimes a small artery in the region of operation is divided, 

 and gives the impression of the carotid having been injured. Injury 

 of the vagus or sympathetic nerve seldom occurs. Perforation of 

 the trachea can only be caused by gross carelessness, but if opened 

 sufficiently for blood to enter the lungs, it might give rise to trouble- 

 some symptoms. 



