BONE SPAVIN. 303 



Btitutes anchylosis for ligamentous union between these bones. In 

 all the actions of the hind leg, from the natural shape of the hock, 

 and more especially in those horses which are naturally " cow- 

 hocked," there is a tendency to yield inwards rather than in the 

 opposite direction. The consequence is that there is more strain 

 upon the ligamentous fibres which connect the scaphoid with the 

 two cuneiform and the internal metatarsal, than upon those uniting 

 the cuboid with the os calcis and external metatarsal bone. Hence, 

 although exostosis does sometimes show itself in other parts of the 

 tarsal bones, it here, as in the fore leg, is almost always confined 

 to what is called the " spavin place," namely, the contiguous sur- 

 faces of the scaphoid, cuneiform, and internal metatarsal bones. 

 In very bad cases the articular cartilage becomes involved, and 

 there is not only an external casing of new bone, but the internal 

 surfaces absolutely coalesce or anchylose. 



The symptoms of spavin are a hard substance showing itself 

 beyond the proper level of the hock joint. There may or may not 

 be lameness, but if bone is thrown out the disease is established. 

 In recent cases whenever the horse is worked he will after rest 

 limp in his action, but the lameness soon goes ofi", and does not 

 show itself again until the part has been sufi"ered to become stiff 

 by a rest of an hour or two. The lameness is very remarkable, 

 and diff'ers greatly from that shown in any other disease. The leg 

 is drawn up with a quick catch, and yet there is a dragging of the 

 limb, indicating not only pain in the joint, but a want of action in 

 it. In the early stages the latter is not clearly developed, but 

 afterwards it is so well marked that a spavin may be pronounced 

 to exist without an examination of the joint. Where lameness is 

 not established, great care should be exercised in pronouncing on 

 the existence of spavin, for some hocks are naturally formed with 

 prominent heads of the internal metatarsal bones, and the inexpe- 

 rienced eye and hand are very apt to mistake these for exostosi?. 

 In such cases, by comparing the two hocks it will generally be 

 seer that they are both exactly alike, while in spavin, although 

 bot' joints may be the seat of mischief, yet they will seldom mani- 

 fest che disease to the same extent. 



The treatment should be directed to the abatement of the inflam- 

 mation which gives rise to the pain, and also to promote absorption 

 of the new growth. Veterinary surgeons are very apt to assert 

 that the disease cannot be cured, and that a spavined horse will 

 always rejuain the subject of it, and therefore/unsound. But prac- 

 tically it is known that many a hock which has been the seat of 

 undoubted spavin loses all external enlargement, and no lameness 

 is shown in it, although tried most severely through a series of 

 years. Still on dissection after death, the ligaments will not show 

 their natural white and glistening structure, and the tarsal bone? 



