DISEASES OF BONES 193 



truth. In very rare instances the inflammatory bony 

 product, as in splint, may disappear. Bone-spavin is of 

 less significance in a heavy draught horse than in one 

 required for Ught work. It is reasonable to assume that 

 very few experts would pass a horse with bone-spavin as 

 sound, provided the animal was under five years of age. 

 It must be clearly understood that spavin represents 

 Nature's method of repairing the damaged part, and the 

 inflammatory action produced and leading to the forma- 

 tion of the spavin very often anchyloses or seals together 

 the smaller bones of the hock joint. The writer is not 

 aware that it ever implicates the true hock joint, i.e. the 

 articulation between the lower end of the second thigh- 

 bone with that of the screw-bone of the hock. (See 

 Structure of Skeleton.) A horse may have one or both 

 hocks spavined and go absolutely sound, or it may have 

 a very small spavin combined with an intractable lame- 

 ness. Horses which are worn and degenerate — members 

 of the old brigade — with spavin commonly go lame, as the 

 disease sometimes takes on not constructive but destruc- 

 tive changes, in the form of ulceration of the cartilages 

 of the joints, etc. Bone-spavin is considered to be a 

 hereditary trouble ; still there are plenty of horses 

 employed for stud purposes, in which unmistakable signs 

 of spavin exist. As to how spavin is caused we have no 

 reliable or authoritative information, but it is probably 

 due to over extension of the hock, to direct injury, such 

 as a blow, etc. The term " Jack- spavin " is practically 

 synonymous with that of " bone-spavin.'' To detect 

 bone-spavin, stand in front of the horse and view the 

 inner and lower aspect of each of the hocks, noting any 

 difference in size. If spavin exists it should be seen as a 

 variable-sized bone prominence in the situation named. 

 Care must be taken not to confuse this with the 

 prominence normally present on the inner aspect of the 

 hock. If the hocks are compared for the existence of 

 spavin, a slight difference in size will be seen, and this 



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