62 



VETERINARY SURGICAL OPERATIONS 



long immersion in a 95% solution of carbolic acid, and then 

 just before inserting it the canula should be passed over the 

 flame of a match. The latter precaution alone is insufficient 

 because the stilletto or trocar within the lumen may not be 

 sufficiently disinfected. The lumen of a canula must be free 

 from needle rust and desiccated particles from previous oper- 

 ations, which may be pushed into the sac during the opera- 

 tion. Once safely cleaned the needle or canula is passed into 

 the sac by one sudden thrust, as the assistant at the head 



Fig. 29 — Special Apparatus for Aspirating Synovial Fluid. 



gives the twitch an extra turn to distract the patient's atten- 

 tion from the seat of operation. 



Third Step. — Abstracting the Fluid. — As a rule the fluid 

 will immediately begin to evacuate freely, but if it fails to flow 

 the stilletto is passed through the lumen to rid it of a possible 

 choke. Failing in this the needle is changed at different an- 

 gles within the sac until success is attained. As the tension 

 relaxes from the evacuation the sac is manipulated with the 

 fingers of both hands so as to bring the remaining fluid under 

 pressure at the entrance point of the needle. This manipula- 



