514 



Joitnial of A'-zricitltnre. 



[9 Sept., 1907. 



and union of the bones, this Latter being the most frequent condition. The 

 bony deposit or outgrowth is the result of inflammatory action in the bones 

 or their covering, and, as with splints, the inflammation and lameness con- 

 tinue until the bones implicated are completely concreted or cemented 

 together in one mass. This union of bones forming a joint is known as 

 " anchylosis," and when it occurs in spavin the actual lameness usually 

 ceases, but there remains a stiffness or want of freedom of hock action 

 plainlv paipal)le tO' the practised eve. 



Fig. 85. — Hock, external aspect — i. Seat 

 of " capped hock." 2. Tibia or leg 

 bone. 3. Calcaneum or heel bone. 

 4. True hock joint. 5. Astragalus. 

 6. Large cuneiform bone. 7. Median 

 cuneiform bone. 8. ("uboid bone. 

 9. Seat of " Curb.'" 10. Head of ex- 

 ternal splint bone. 11. Metatarsal or 

 hind Gannon bone. 12. Perforatus 

 tendon. (After Haves.) 



Fi^f. 86. — Hock, internal aspect — i and 

 2. Tendo achilles (Perforatus tendon 

 and gastrocnemius tendon). 3. Per- 

 forans tendon. 4. Tibia. 5 and 6. 

 Calcaneum. 7. Perforatus tendon. 

 8. Perforans tendon, g. Cuboid bone. 

 10. Astragalus. 11. I^arge cuneiform 

 bone. 12. Median cuneiform bone. 

 13. Small cuneiform bone. i.^. Head 

 of internal s])lint bone. 15. Large 

 metatarsal or hind cannon bone. 

 (After Haves.) 



Spavin may develop at almost any age, but it is most common in 

 immature or " growing " horses under six vears ; and in these, is a less 

 serious affair. In aged horses with hardened Iwnes a spavin takes a much 

 longer time to "set," the accompanying lameness is much more persistent, 

 and treatment is not likely to be so effective. 



Causes. — Jar or concussion is usually considered to be the most impor- 

 tant factor in the causation of spavin, but its effect in determining the in- 

 cidence of the disease is not sufficiently clear to warrant dogmatic assertion 

 on the point. It must, however, be conceded that, on account of the 

 peculiar shape and disposition of the bones of the hock, the small bones 

 at the seat of spavin are subjected to a vibratory jar, additional on that 



