2l6 THB HORSB. 



Sand-cracks sometimes commence on the internal face of the wall, in- 

 volving its whole thickness, excepting a thin layer on the outer surface. 

 In those cases the existence of the injury may be suspected from a sUght 

 depression, which begins near the coronary band and follows the direc- 

 tion of the horny fibers, but the trouble can only be positively diagnosed 

 by paring away the outside layers of horn until the fissure is exposed. 

 In toe-cracks the walls of the fissure are in close apposition when the 

 foot receives the weight of the body, but when the foot is raised from 

 the ground the fissure opens. In quarter-crack the opposite is true, and 

 the fissure closes when the weight is removed from the foot. As a rule 

 sand-cracks begin at the coronary band, and as they become older they 

 not only extend downward, but they also grow deeper. In old cases, 

 particularly in toe-crack, the horn on the borders of the fissures loses its 

 vitality and scales off, sometimes through the greater part of its thick- 

 ness, leaving behind a rough and irregular channel extending from the 

 coronet to the end of the toe. 



In many cases of quarter-crack, and in some cases of toe-crack as well, 

 if the edges remain close together, with but little motion, the fissure is 

 dry, but in other cases a thin, offensive discharge issues from the crack 

 and the ulcerated soft tissues, or a fungus-like growth, protrude from 

 the narrow opening. 



When the cracks are deep and the motion of their edges considerable, 

 so that the soft tissues are bruised and pinched with every movement, 

 a constant inflammation of the parts is maintained and the lameness is 

 severe. 



Ordinarily, the lameness of sand-crack is slight when the patient 

 walks ; but it is greatly aggravated when he is made to trot, and the 

 harder the road the worse he limps. Furthermore, the lameness 

 is greater going down hill than up, for the reason that these 

 conditions are favorable to an increased motion in the edges of the 

 fissure. 



Treatment. In .so far as preventi^'e measures are concerned but lit- 

 tle can be done. The suppleness of the horn is, of course, to be main- 

 tained by the use of ointments, damp floor, bedding, etc. The shoe is 

 to be proportioned to the weight and work of the animal ; the nails hold- 

 ing it in place are to be of proper size and not driven too near the heels ; 

 sufficient calks and toe-pieces must be added to the shoes of horses 

 working on slippery roads, and the evils of jumping, fast driving, etc., 

 are to be avoided. 



