302 



PARTICULAR LAMENESSES. 



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

 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. 1st. 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 they are 

 all more or less so. 



Bone-spavin is but very rarely 

 found on the outer side of the hock. 



Fig. 50. — Showing situation -n-n j-ia-i, u j-v 



of bone-spavin, a shallow groove Percivall says that he would not be 

 being left in the ossific deposit gure " that an exostosis upon the out- 



for the passage of the oblique . -, iii ni • i 



tendon of the flexor metatarsi, Side would be Called a spavm, and 



immediately under which the that it is COmmonly the rCSult of 

 spavin is situated. . . ,, i , t i 



injury; but I have a specimen m 

 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. 



Spavin arises from causes that are hereditary or constitu- 

 tional and local. 



