344 Journal of Agriculture. [ro May, 1910. 



ill aliout the same proportion as recorded abo\-e concerning sidebones in 

 the fore and hind feet respectively oi draught horses. Incidentally, it 

 may be mentioned that the form of hoof in which sidebone has been most 

 frequently found, is that in which the wall — particularly at the sides — 

 approaches the perpendicular. Such feet are also usually small, narroAv 

 and blocky. Sidebones are seldom associated with large and spreading 

 or broad and flat feet. 



As .regards B, the fact of the sidebone occurring in both fore feet 

 more than three times as frequently as in a single foot, indicates an intrinsic- 

 causation rather than causation by external yiolence. which would scarcely 

 happen to both fore feet simultaneously. 



Comment on C may be confined to the statement that the excess ot 

 sidebones found in the off feet, as compared with the near, is so slight (10 

 to 9) that it cannot lie regarded as of any significance in the matter of 

 determining the causation of sidelione. The observation, hovvever, con- 

 flicts with 'the statement in Mollar and Dollar's Veterinary Surgery, that 

 " the cartilage of the left foot suffers more freauently than that of the 

 right.' 



Observation D is of considerable importance. The fact that the dis- 

 paxity between the incidence of sideline on the outside and inside of the 

 foot is SO' slight (only as 8 is to 7) would appear to indicate the falsity 

 of a commonly held supposition, viz. : — that sidebone is regularly caused 

 by an injury sustained through the dropping of the shafts on to the 

 coronets when the horse is lieing unvoked from a dray, or from the 

 coronets being trod on when working in a team. In the former case, it 

 is obvious that only the outside coronets could sustain injury, but in neither 

 case can such a cause be admitted as regards the horses under review. 

 Being stud horses and many of them of high value, it may be asserted 

 that not one in ten of the draught horses examined had e\'en been yoked 

 to a dray or harnessed in a team, or even worn a colJai. 



On this theory of injury as a cause of sidebone, it may be remarked 

 that the number of occasions on which any evidence of external injurx 

 having been sustained, suiii as a scar, is practically negligible; on the 

 other hand, some of the draught sires and many of the trotting sires 

 examined ha\e shown sca.rs over the seat of sidebone but without an\ 

 ossification of the cartilage having occurred. This was notably the case 



\\ith the pony " D S '' whose near fore coronet outside had 



apparently at one time been literally cut to pieces, yet w-ithout even stiffen- 

 ing the cartilage. In cases of Quittor it fre<]uently hapjiens that the 

 inflammatory process involves the lateral cartilage to the extent that 

 suppurating sinuses mav pierce it, and the cartilage still remains free 

 from ossification. I doubt whether sidebone is ever caused by external 

 violence per sc, and I do not think that even deliberate bruising of the 

 coronets of a light horse by severe hammering would result in ossification 

 of the underlying cartilage. Amongst hundreds examined, I have never 

 seen any specimen showing evidence of ossification having commenced at 

 the summit or margins of the cartilage. It always comiiiences at the base 

 where the cartilage is joined to and rests on the wing of the pedal bone 

 and gradually extends upwards throughout the substance of the cartilage 

 to the summit and borders. Many specimens are in my possession showing; 

 all stages of growth of sidebone from the very commencement at the base 

 of the cartilage, through gradations in size of the ossified portion to the 

 fully formed sidebone involving the whole of the cartil;;ge. I have never 

 been able to find a specimen of bon\ formation at tlie top of the cartilage 



