POSTERIOR MEMBER. 289 



result of contusions and have little gravity ; they are in most instances absorbed 

 spontaneously, are much more rare, and only appear accidentally at all periods 

 of life. 



Splints occur more often upon the anterior members than upon the posterior, 

 and on the internal side than the external. This is due to their cause of develop- 

 ment. They proceed, in fact, from tractions exerted on the interosseous ligament 

 under the influence of the vertical pressure which is exercised on the head of the 

 splint bones during rapid locomotion. As long as these small bones axe-not 

 soldered to the principal bone in consequence of the normal ossification of their ' 

 ligament of union, they tend to glide up and down in a measure proportional to 

 the weight which they sustain. Whence results rupture of the ligamentous 

 fibres, which is propagated to the periosteum, irritates the latter, and causes a 

 periostitis with the appearance of one or more tumors upon the tract of the 

 rnetacarpal or metatarsal synarthrodial articulations. 



It is easily understood from this that tne formation of splints is a disease 

 more frequent in young horses used too young, and without moderation, for 

 heavy work, than in old horses, in which the process of co-ossification of the 

 bones of the canon has already been completed. It can also, without difficulty, 

 be perceived that they should be more common on the anterior limbs, nearer to- 

 the centre of gravity, which receive, more especially, the effect of the quantity 

 of movement at great speed. Finally, it is equally easy to explain their habitual 

 presence upon the internal side if we only recall : first, that the weight of the 

 body presses more upon the internal side of the articulation ; second, that the 

 pressure sustained by the bones is proportional to the area of compressed sur- 

 faces. Now, in this connection, it is to be remarked that, all proportions being 

 considered, the articular surfaces of the internal metacarpal or metatarsal bones 

 are larger than their homologues of the external side; whence it follows that 

 these bones are more disposed to glide against the median piece which supports 

 them than the external, and, consequently, to lacerate their interosseous ligament. 



Splints, the volume of which varies from that of a small hazel-nut to that 

 of a hen's egg, are characterized externally by the relief which they form under- 

 neath the skin, and by a sensation of hardness which is conveyed to the hand on 

 palpation. They are readily perceived if the canon be viewed from in front. 1 



Their disposition is very variable : sometimes only one exists (simple splint) ; 

 sometimes there are two, situated almost on the same level on each side of the 

 region (pegged splints) ; at other times there are several in succession from above 

 downward, upon the same face, and of an almost uniform volume (chain splints) ; 

 finally, there are some which, in relation to size, form a decreasing series from 

 above downward, on the one side or the other (spindle-shaped splints). 



Whatever may be their form, these tumors are more grave as they are situ- 

 ated towards the carpal or the tarsal articulations, or are developed in the posterior 

 gutter destined to lodge the suspensory ligament of the fetlock. In this case they 

 cause an evident constraint and induce too often a persistent lameness. Most 

 ordinarily a splint lames a horse, only at the first, when the inflammatory process 

 of the periosteum is still in full activity. The lameness disappears as soon as 

 the tumor is quite developed. * 



1 The buttons of the rudimentary metatarsal or metacarpal bones should not be mistaken 

 for splints. 



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