138 



PARTICULAR FRACTURES. 



when it has been nearly worn through by the caries of chronic 

 navicular disease. Very often this fracture is accompanied by 

 rupture of the diseased portion of the tendo perforans, and in 

 such a case the toe is immediately turned up, making the diag- 

 nosis certain ; when this complication is not present, it is more 

 difficult to arrive at a sure conclusion, and the history of the 

 case must be taken into account. The horse has been lame, but 

 serviceable, for a long time, and all at once he becomes help- 

 lessly lame and unfit for further use. The practitioner must 

 draw his own conclusions, and reason upon the case, as no set 

 rule can be laid down. 



This form of fracture occurs very often after the operation of 

 neurotomy, from the increased freedom of motion which results 

 upon the removal of pain ; both tendon and bone giving way, 

 the fetlock coming to the ground, &c. I have seen one case that 

 goes to prove that mere fracture of the bone after this operation 

 does not always cause inconvenience to the animal; and sub- 

 joined are two woodcuts, of the navicular bone from a horse 



Figs, 15 and 16 show both surfaces of the Navicular bone, 

 described in the text. 



unnerved by me at the Veterinary College more than three years 

 before he was destroyed. During the whole of that time he 

 performed his worlv well and soundly, and ultimately had to be 

 put away, owing to the occurrence of necrosis of the os j^edis. 



