AND HIS DISEASES. ] 3 



ticulations — ^viz., one between the cannon and middle wedge- 

 bone ; one between the middle and great wedge-bone ; one 

 between the great wedge-bone and the astragalus ; and the 

 true hock-joint, between the astragalus and the tibia. The 

 former do not possess any very extensive motion, serving 

 more to break concussion. It must be remembered that all 

 these joints have their own capsular and binding ligaments. 

 The surface of the bones are covered by artibular cartilage, 

 and lubricated by synovia, or joint-oil. Need we wonder, 

 then, that a structure so complex should present a corre- 

 sponding complexity in its diseases ? 



/ The seat of spavin, arising from inflammation of the peri- 

 osteum, is generally between the head of the cannon and the 

 inner splint-bone. The author of the " Horse " thus very 

 plainly accounts for this : — " The middle wedge-bone rests 

 upon the cannon-bone, and the smaller wedge-bone rests in 

 a very slight degree on the shank-bone, but principally, or 

 almost entirely, on the inner spHnt-bone. Then, the splint- 

 bone sustains a very unequal degree of concussion and 

 weight. Not only is the inner one placed more under the 

 body, and nearer the centre of gravity, but it has almost the 

 whole weight and concussion communicated to the little 

 wedge-bone carried on to it. / It is not, therefore, to be won- 

 dered at, that in the violent action of this joint in galloping, 

 leaping, heavy draught. and _£S]2 ecially in young horses, and 

 before the limbs have become properly knit, the inner splint- 

 bone or its ligaments, or the substance which connects them 

 to the shank-bone, should suffer material injury." 



The plausibility of the above reasoning is evident, and 

 many cases of spavin arise in this way ; and the process ' of 

 inflammation ^oe s on, nssif yirnr t.hp gplint. to the c .f f.rvean n^ 

 extending upwa rd, inYolvi ng_thp wpdge,-b"Tip.s^ anmm-.iiTnpg 

 producing anchylosis, or complete union between these 



