8o PUNCTURE OF THE INTESTINES. 



at the most prominent part of the distension. After the 

 skin at this place has been clipped or shaved and disinfected 

 grasp the trocar with the index finger and the thumb of the 

 left hand and holding the instrument perpendicular to the 

 skin, give it a firm quick blow with the palm of the right 

 hand and drive it through the abdominal walls into the 

 intestine. With a properly constructed trocar of the dimen- 

 sions suggested in Figure 5 no preliminary puncture with 

 the lancet is required or advisable. The cutting end of the 

 stilette should be very long, tapering and sharp so that it 

 will cut as freely as the lancet. By performing the opera- 

 tion as directed the trocar ordinarily punctures the caecum. 



FIG. 5. 



Intestine trocar with sheath. Outside diameter of canula 3 mm , 

 length of canula, 16 cm. 



Withdraw the stilette and permit the gas to escape through 

 the canula. The canula may become occluded by particles 

 of ingesta entering it and these should be removed by rein- 

 serting the stilette. The intestine first punctured may 

 collapse and the flow of gas cease while the tympany con- 

 tinues in other parts ; this may be overcome by reintroducing 

 the stilette and pushing the trocar through the distal wall of 

 the bowel and into the next section of intestine beyond. 

 If this does not succeed the trocar may be withdrawn and 

 reinserted in a neighboring area or if need be on the opposite 

 side of the .animal. In withdrawing the canula replace the 

 stilette and press the skin against the abdominal with the 

 thumb and finger of one hand while the trocar is drawn out 

 with the other. This tends to prevent particles of ingesta 



