678 OPEEATIONS. 



1902), states that" although it has been my fortune to tap hundreds 

 of horses, I have never been troubled with subsequent suppuration, 

 and I attribute this largely to the practice of invariably puncturing 

 in a downward direction, and from a point as high up as possible." 

 If the first puncture^ — owing to blocking up of the cannula, to its 

 being too short, or to the intestines being filled with solid matter — 

 does not succeed; we may repeat the operation a little above or 

 below the first puncture, on the left side, or where we perceive the 

 accumulation of gas to be greatest. Many authorities agree that 

 the puncture can be made without danger on the left side. 



In order to injure the intestines as little as possible, and to 

 prevent the chance of particles of food getting into the abdominal 

 cavity, and thus setting up peritonitis, we should use an instrument 

 of small diameter. In fact, the smaller the diameter of the can- 

 nula, other things being equal ; the less risk is there in the opera- 

 tion. 



For securing the animal, it is generally sufficient to tie up one 

 fore leg, and to apply a twitch. We ought, if possible, to take 

 the opportunity of making the puncture when the animal is lying 

 down, and should carefully guard against the chance of injury to 

 the horse, while the puncture is being made, from his throwing 

 himself about when suddenly seized with colicky pains. The 

 animal can be kept lying down by means of hobbles. 



The operation itself is a very simple affair. The operator, having 

 placed himself on the right side of the horse, should make an in- 

 cision through the skin with the knife, at the point chosen, of a 

 little less than half an inch in length, in order to allow the trocar 

 to penetrate easily, and to prevent air getting into the loose tissue 

 underneath the skin. Then, while holding the instrument with 

 his left hand, he should place its point into the incision, at right 

 angles to the surface of the skin, and should strike the handle a 

 sharp blow with the palm of the right hand, so as to make the 

 point of the trocar penetrate the intestine. The gas escapes with 

 violence on the trocar being withdrawn out of the cannula. In pro- 

 portion as the gas escapes, so does the inflation of the intestines 

 diminish. We should take care to press the cannula as far as it 

 will go, so that its lower end may be in the intestine, and may 

 not remain between it and the flank. If the escape of gas stops 

 suddenly, on account of the cannula becoming obstructed, the in- 

 strument should be mopped out by means of a small metallic steim 

 prepared for that purpose, but not with the trocar, which might 

 wound the intestine. If these means do not succeed, a second 

 puncture, some distance from the first one, may be made. 



The cannula should be kept in until the gas ceases to escape and 

 the inflation has nearly disappeared. It is always prudent not to 



