150 OPERATIVE TECHNIQUE. 



though it is difficult to know why the ordinary interrupted suture 

 should so entirely have been displaced for this purpose. A word 

 of caution is required against using hairs from the mane or tail 

 to complete the suture, as was the old fashion. These hairs not 

 infrequently formed the centre from which radiated an acute phlebitis. 



The jugular vein lies in the "jugular furrow," formed above by 

 the mastoido-humeralis and below by the sterno-maxillaris muscles. 

 Beneath the skin and loose connective tissue lies the panniculus, 

 which, though very thin in the upper portions of the neck, becomes 

 over half an inch in thickness in the lower. In the upper half 

 of the jugular furrow " the vein rests on the subscapulo-hyoideus 

 muscle, which there separates the vessel from the carotid artery ; 

 but in the lower half the vein rests on the side of the trachea, and is 

 in direct contact with the carotid, which lies above and slightly 

 internal to it " (see Fig. ig8). On account of this arrangement the best 

 position for opening the vein without endangering the carotid artery 

 is at the division between the upper and middle thirds of the neck. 



Operation on the horse. — When using the spring fleam it is of little 

 importance on which side the operation is performed, though some slight 

 advantage accrues from selecting the right. The same is true of the 

 lancet, but the fleam can be used most conveniently on the left. At 

 the junction of the upper and middle thirds of the neck a small 

 area of skin should be shaved and disinfected. This preparation 

 minimises danger of phlebitis. (Figs. i8o and i8i.) The horse is 

 then bridled, and the head held exactly in the middle line by an 

 assistant. Troublesome horses may be twitched, and the fore-foot 

 on the side of operation may be lifted. \\'hen using the ordinary 

 fleam the horse's eyes should be covered, because at the moment 

 of striking the blow the animal is apt to start, defeating the 

 operator ; but of course this is not likely to occur in using the 

 lancet or spring fleam. Having cocked the spring fleam, the 

 operator stands beside the animal's shoulder, and with the thumb 

 or fingers of the left hand compresses the vein, causing it to rise. 



Should there be any doubt as to the exact spot to select, the 

 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, and 

 the vein compressed below the incision until the necessary quantity 

 of blood has been taken. 



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



