302 



PAETICULAK LAMENESSES. 



defined to be an exostosis on the inner and lower part of tbe 

 hock, arising from inflammation of the cuneiform and metatarsal 

 bones, terminating generally in anchylosis of one or more of the 

 gliding joints of the hock. 



Why spavin should generally appear on the inner, and but 

 rarely on the outer side of the hock, can be explained by satis- 

 factory reasons. Ist. The inner side of the limb is more under 

 the central line of gravity: 2d. From the arrangement of the 



cuneiforms, and especially the direc- 

 tion of the articular surface of the 

 astragalus, the hock is so constructed 

 that when the limb is flexed the 

 pressure and consequent concussion 

 is thrown on the inner side. Pro- 

 fessor Goodsir maintained that , a 

 screw-like motion of the true hock- 

 joint, acting unfavourably on the 

 cuneiforms and metatarsals, was the 

 cause of spavin. Professor Barlow 

 said spavin was due to compression 

 of the cuneiforms during extreme 

 flexion. Other pathologists maintain 

 that concussion, produced when the 

 -foot comes forcibly to the ground, 

 is the sole cause. It is not my in- 

 tention to discuss which theory is 

 correct. In all probability tliey are 

 all more or less so. 



Bone-spavin is but very rarely 

 found on the outer side of the hock. 

 Percivall says that he would not be 

 sure " that an exostosis upon the out- 

 side would be called a spavin, and 

 that it is commonly the result of 

 injury ;" but I have a specimen in 

 my possession, presented by Mr. Stevenson of Newcastle, with 

 a spavin in this unusual position, originating from no apparent 

 cause, and which produced an incurable lameness ; but I have 

 seen several cases from which the lameness entirely disappeared. 

 Spavin arises from causest that are hereditary or constitu- 

 tional and locaL 



'rio.^50. — Showing eituation 

 ^of bone-spavin, a BhaUow groove 

 being left in the ossific deposit 

 for the passage of the oblique 

 tendon of the flexor metatarsi, 

 immediately under which the 

 epavin is situated. 



