NAVICULAB-JOINT LAMENESS. 781 



sole is thin and the frog prominent, because of the increased pres- 

 sure upon the frog, and thence upon the parts involved, by the 

 foot setting into the ground. As the lameness continues, more or 

 less change of structure takes place in the foot, a gradual draw- 

 ing in of the quarters, the foot becoming perceptibly smaller than 

 the opposite one, the heels higher, the frog smaller, and the sole 

 more concave, the hoof showing a more glossy, hard appearance. 

 The shoe will invariably be worn round at the toe. A result that 

 often follows is a shrinking or wasting of the muscles of the 

 shoulder, called "sweeny," which is caused by a want of properly 

 exercising them. The symptoms are about the same, so far as the 



FIG. 689. Back view of coffin-bone and navicular-bone 

 attached in place. 



lameness goes, whether the mischief has extended to ulceration or 

 not, the history of the case only guiding in enabling to deter- 

 mine how far this has gone. Of course these conditions will vary 

 in degree, as there may be only a slight extent of ulceration, or a 

 high degree of simple inflammation. Yet, in the former case, the 

 lameness will not be so marked as in the latter, notwithstanding 

 the prospect for recovery will be much less. 



We will now presume a horse, without any apparent cause, to 

 show a little lameness, and we desire to make a careful exam- 

 ination. First, is there any possible cause from recent shoeing, 

 such as a badly-fitted shoe, driving the nails too close, or prick- 

 ing ? Let the shoe be taken off carefully, by raising each clinch 

 in succession, and pulling the nails out. Now tap and examine 

 all parts of the foot carefully, and especially if there is any bruise 



