SPAVIN. 



257 



ferent bones of a joint never toiicli each other; as they are 

 separated by articular cartilage. In ordinary bone spavin, this 

 cartilage becomes ulcerated as the result of inflammation extending 

 from the bones, and is finally absorbed ; the exudation thrown out 

 from the blood-vessels of the bones being converted into bony 

 material, which causes bony union and consequent destruction of 

 the joint. Here, we have a reparative process with cessation of 

 inflammation. In occult spavin, on the contrary, the process stops 

 short at ulceration, and no reparative action takes place ; hence, 

 the serious and intractable nature of this form of the disease. 



TendoJh of 

 gastrocnemhxs extemas.^ 



Perfariuis tendoTi 



Tibi 



CL 



Astragaiu^. 



Laiye ciuiei/orm - 

 Median ciaieifimn. _ 



Large metatarsal 



{ CaiUKOTV) 



PerfoTotus teitdoiv 



Os ailcis 



X-Os culvis 



- -Perforatus 



Perfbrans 



' l- - Cuboid- bone' 



Small cuneifbmv 

 _ . Small sjduit borie^ 



Fig. 98. — Inner side of off hock. 



Occult spavin is naturally much more common in old, than in young 

 horses; for, in the latter, repair is much more active than in 

 the former. As the inflammation, and not the deposit, consti- 

 tutes the disease, we must regard bone and occult spavin as one 

 and the same complaint. 



SYMPTOMS. — The lameness of spavin is characterised by want 

 of freedom in bending the hock, which causes the horse to " drag 

 his toe " and to wear the hoof at that part (Fig. 1) ; and by the 

 lameness getting better as he " warms up " at exercise. In severe 



17 



