88 FISTULA AND POLL-EVIL 
be watched more carefully. They must not be 
allowed to close above before sequestration 1s 
complete and the bone is in condition to cica- 
trize with the rest of the wound. It is here 
that recurrences occur. Stumps of bare verte- 
bre are covered by scar tissue and cause a re- 
accumulation of pus which will require subse- 
quent attention if not a second operation of 
equal magnitude. 
During the healing of the wound its walls 
are scrutinized daily for shreds of ligament 
that are becoming surrounded with granula- 
tions before detaching from their viable con- 
tinuation. It often happens that large sloughs 
of ligamentous or new-formed fibrous tissue 
appear here and there about the cavity as cica- 
trization proceeds. These delay healing and 
should be removed as soon as possible. 
At the end of five weeks we usually dispense 
with the tube and apply such simple astring- 
ents as a two per cent solution of zine sul- 
phate or common white lotion. At this time 
horses may be worked with breast harness 
but collar pressure directly upon the region is 
not admissible until after three months have 
elapsed. 
Modifications 
Large subcutaneous or subfascial abscesses 
are evacuated at dependent points and drain- 
