148 LAMENESS IN THE HORSE. 



the frog. Thrush of long standing is occasionally followed 

 by a characteristic ridge formation of the wall, the ridges 

 running in all directions, even crossing each other. 



9. — Sandcracks. 



Inspection. — Cracks in the horny wall do not frequently 

 cause lameness, except those which begin one or two inches 

 below the coronary cushion extending into it ; in such cases 

 lameness is quite common. Animals with cracked hoofs 

 occasionally show a periodic lameness when the hoofs are 

 exposed to prolonged drying or moisture, the lameness 

 simply resulting from the drying or softening of the edges 

 of the crack, with subsequent irritation of the underlying 

 sensitive parts. Any serious lameness in cracked hoofs is 

 due to the introduction of septic material into these cracks, 

 which frequently causes superficial, or even parenchymatous, 

 inflammation of the podophyllous membrane. Brittle, con- 

 tracted, crooked and flat hoofs are particularly predisposed 

 to sandcracks. 



Palpation — It is always advisable to carefully search the 

 hoof for cracks in cases of hoof lameness, and since such 

 cracks maybe hidden by mud, wax, gutta-percha, etc., minute 

 inspection is necessary. 



10 — Loosening of the Sole from the "Wall. 



Inspection— Lameness, chiefly on hard ground, accom- 

 panies separation of the sole from the wall only when the 

 break extends into, or close to, the sensitive sole, or if, as a 

 consequence of septic material entering this space, inflam- 

 mation of the podophyllous membrane sets in. This trouble 

 is mostly seen in the fore-legs of flat footed horses. In old 

 cases, with extensive separation of these structures, one 



