SETONING. 171 



point of the needle is then grasped with fingers or forceps and with- 

 drawn through the upper orifice, bringing with it the tape with 

 which it has been threaded. If, however, the eye is in the point of 

 the needle the tape is not inserted until the eye appears through 

 the upper wound. The tape is then passed and the needle with- 

 drawn, leaving the tape in position. The tape, which must be at 

 least twice as long as the seton track, is secured by firmly tying the 

 ends together or by attaching each end to a transverse piece of 

 rubber tube. The disadvantage of uniting the ends consists in the 

 danger of the loop so formed catching on a hook or other object or 

 being grasped in the horse's teeth, and the seton being torn out. To 

 prevent this the horse should be tied up or a side-stick applied. In 

 dogs a muzzle must be put on. 



To increase the action the seton is smeared with an irritant, and 

 is daily moved to and fro. As soon as pus forms, free drainage 

 should be secured by fomenting the orifices daily and gently stroking 

 the channel from above downwards. The seton may be left in 

 position from eight to twenty-one days. To remove it the upper 

 end is snipped off with scissors and the tape drawn downwards. If 

 left too long in position ulceration and sloughing of the skin over 

 the seton may be produced. 



Inserting a frog seton demands certain special precautions. The 

 horn around the point of the frog having been thoroughly thinned, 

 an incision is made above the bulbs of the heel, and the special 

 needle, with its convex side towards the tendons, is thrust down- 

 wards through the plantar cushion towards the point of the frog, 

 the foot meanwhile being extended as far as possible. The needle 

 should appear near the point of the frog. The ends of the tape are 

 knotted together and a dressing applied. 



In passing setons, blood vessels may be wounded, but as only 

 small twigs are usually affected no special precautions are called for. 

 Where nerves are injured paralysis may result, and in some cases 

 tendon sheaths and joints have been opened. The passage of a 

 seton under fascia?, or the panniculus may be followed by extensive 

 suppuration, with abscess formation at some distance from the seton. 

 Occasionally, and especially during summer, infection of the seton 

 track occurs with extensive inflammatory oedema — which may lead 

 to a fatal result. After removal of the seton, the wounds may 

 granulate excessively, producing considerable deformity of the part ; 

 in that event the wounds should be treated by compression, dried 

 alum, or the actual cautery. 



