108 VETERIN ART DENTAL SURGERT. 



operation, using a ^ inch trephine, cutting through 

 and removing the external bony plate. We found 

 underneath it a piece of necrosed bone, about as large 

 as a good sized pea. We made a careful examina- 

 tion of the wound, but could not find that the sinus 

 extended any deeper. The wound did very well, 

 and in a few days healed up nicely, but much to our 

 disappointment only remained so a short time, when 

 it broke out and discharged the same as before. We 

 were then very certain that we had made a mistake 

 in our diagnosis, and that the tooth must be involved ; 

 yet examination by the mouth did not help us to 

 diagnose the difficulty. However, we advised the 

 removal of the tooth, but the owner of the horse 

 would not consent. He then placed the animal 

 under the care of Dr. Craig who said the tooth was 

 perfectly sound, and that the sinus could be healed in 

 a few weeks. After treating the horse for three 

 months with no better results than ours, he was 

 returned to the owner. The following November I 

 was again called to see the horse, and could then 

 pass the probe three inches into the pulp cavity of 

 the tooth. This convinced the owner that the tooth 

 was unsound, and I was asked to extract it. On 

 account of the age of the horse (six years), the teeth 

 being very long at this time, I decided to trephine 

 and drive the tooth out. As we already had a sinus, 

 all we needed to do was to enlarge the opening 



