CONTRACTION OF THE FOOT. 



341 



hoofs the frog sometimes becomes compressed by the bars (fig. 

 331) ; this is not infrequently the forerunner of contraction. 

 Just as the space occupied by the frog diminishes, the direc- 



FlG. 331.— Strangulation of the frog by the bars. 



tion of the walls at the heel alters. The heels gradually 

 encroach on the frog, converging from the coronet towards the 

 bearing surface ; they draw together either in an equal degree 



Fig. 332.— Excessive contraction of heels. 

 The frog has almost disappeared. 



Fig. 333.— Unilateral contraction. 



(fig. 332), or one to a greater extent than the other (fig. 333). 

 It must not be supposed, however, that every hoof in which 

 the walls at the heel converge is a contracted hoof, because, 



