8 June, 1907.] 



Lameness in Horses. 



373 



the short pastern bone immediatelv at the junction of hoof and skin. 

 Being so situated low rin}i;bone is a much more serious affair than high 

 ringbone on account of the fact that the bonv outgroAvth is compressed 

 between the bone and the unyielding rim of the hoof. The pain and 

 lameness are consequently extreme; the irritation, kept up continuously 

 by the compression, prevents the inflammation from subsiding. Conse- 

 quently the ringbone seldom "sets" and the bony outgrowth spreads until 

 the pastern joint (just aboye the hoof) becomes involved in the process 

 and finally stiffened by bony union. Rendering the horse practically use- 

 less for a long period, as it does, it is fortunate that low ringbone is the 

 less common of the two forms. (See Figs. 39, 40, 41, and 43.) 



Causes. — Th-? causes of ringbone are not so well defined as most other 

 bone lamenesses. It has been held that concussion cannot be a comm.Mi 



^'^n- i''- Il'f^I^ ringbone with complete 

 union of the long and short pastern 

 bones. 



Fif,'. 40. Low ringbone with 

 complete union of short 

 pastern bone and pedal bone. 



cause because the fore ])asteins are not more frequently affected than tli * 

 hind, if as frequently ; but holders of that \iew fail to recognise there is 

 a difference between " weight-shock " and " jar," and that the latter affects 

 the hind limbs as much as the fore. Anyhow it is ahvavs in horses with 

 short and upright pasterns that ringbone occurs, and in these the jarring 

 of the pastern during progression is much greater than in horses with long 

 and springy pasterns. The occurrence of ringbone on the hind pastern is 

 often associated with contracted tendons in which the pastern is kept more 

 upright and toe is stubbed into the ground at each step. In such cases 

 there can be no doubt that the concussive jar on the upright column of 

 bones is the cause of the ringbone. Other causes include sprain of the 

 ligaments of the pastern and coffin joints, stich as is sustained diu-ing a 

 sidewards slip or wrench. 



