•8 July, 1907.] 



Lameness in Horses. 



421 



thrown further forward than natural, and the heels always come to the 

 ground first; this with the object of avoiding weight being put upon the 

 toe, where there still remains some sub-acute inflammation and pain. At 

 the same time the length of the step is shorter than usual although the 

 exaggerated action gi\es the opposite impression. Another feature of lame- 

 ness from laminitis is that the lameness increases with exercise whereas 

 with some other diseases of the foot — navicular disease for instance — the 

 lameness passes away when the animal is "warmed up." 



There are also chronic changes in the shape of the hoof which are 

 usually so well marked as to stamp the animal at once as having been 

 foundered. These changes result partly from the original disease and 

 partly from the manner of progression above described. At the time of the 

 existence of the inflammation the swelling inside the hoof around the 

 pedal bone causes pressure to be exertt-d oii the front part of that bone 



"I 



Fig. 61. Gi- 



on horse's hoof. (After Hayes.) 



whereby it is given a downward direction. (See Fig. 58.) The sole 

 is consequently pressed downwards and becomes flatter than natural. In 

 some cases the downward pressure of the pedal bone causes the sole to 

 become convex and the condition known as " dropped sole " or " pumiced 

 sole" is produced. (See Figs. 58 and 59.) On account of the fact that 

 foundered horses "go on the heels " a more active growth of horn at the 

 heels is induced and the heels therefore are deeper than normal. At the 

 same time the front of the hoof instead of maintaining the natural straight 

 contour from the coronet to the ground surface, becomes " dished " or 

 concave in contour and the toe has a tendency to turn upwards. This 

 increased growth of horn at the heels is intermittent and consequentlv there 

 are produced a succession of rings round the hoof which differ from " grass 

 rings " in that they are wider at the heels. (See Figs. 60, 62, and (i2>) 

 Often they may be one-half or three-eighths of an inch in thickness at the 



