292 



OPERATIONS ON BONES. 



Fig. 306.— Scissors. 307.— Bistoury. 308.— Periostome. 309.— Seton Needles. 



sometimes substituted; a periostome (Fig. 308), a kind of blunt 

 bistoury, narrow and curved; and two flat needles (Fig. 309), 

 short and curved flatwise, one of which is blunt, and used to di- 

 vide the connective tissue, the other being sharp and to be used 

 as a seton needle to pass a tape into the subcutaneous incision, if 

 it is judged necessary. These needles may either be inserted into 

 a handle, or used free. 



The operation is a simple one to perform. The animal being 

 cast and properly secured, an incision is made with the rowell 

 scissors or the bistoury, at the most dependent parts of the bony 

 growth, large enough to allow the introduction of the blunt curved 

 needle. This being pushed slowly under the skin, separates it 

 from its attachments, and ui^on being gradually withdrawn, the 

 periostome is passed into the tract thus formed, directly over 

 the bony tumor. Turning the sharp edge of the periostome on 

 the exostosis, and pressing it over the periosteum, this is divided 

 by subcutaneous strokes down to the most superficial layer of the 

 exostosis, which may be incised by the instrument. 



When the tumor is of long standing, a seton may be intro- 

 duced by pushing into the tract, from which the periostome has 

 been removed, the curved needle which carries the tape, and it is 

 brought out by an opening made at the highest part of the tumor. 



SeweU claims that after twenty-four hours the parts become 

 the seat of a large swelling, and more or less inflammation may take 

 place, but after twelve days the animal is ready to resume his 

 work, the swelling ha\Tng gradually subsided, and the lameness 



