DISKASES OF THE FETLOCK, ANKLE, AND FOOT. 433 



Fast work on hard roads. juiniMiip:. and blows on the coronot. 

 t<)«rether witli calk wounds of the feet, are accidental caiist^'s of (juar- 

 ter cracks in particular. Toe cracks are more likely to oe caused by 

 heavy pullincf on slippery roads and pavements or on sti'ep hills. 



t'<l//npfonis. — The fissure in the horn is ofttimes the only evidence 

 of the disease; even this may be accidentally or purposely hidden 

 from casual view by nuul. ointments, tar. wax. putty. <ruttii-pci(ha, 

 or by the lon<j: hairs of the coronet. 



Sand cracks s<imetimes connnence on the internal face of the wall, 

 involvinjr its whole thickness excejitino; a thin layer on the outer 

 surface. In these cases the existence of the injury may be suspect^'d 

 from a slight depression,Avhich begins near the coronary band and 

 follows the direction of the horny fibers; but the trouble can only be 

 positively diagnosed by i)aring 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 quar- 

 ter crack the opposition is true; the fissure closes when the weight is 

 renioved from the foot. As a rule, sand cracks begin at the coritnary 

 band, and as they become older they not only extend downward. Init 

 they also grow deeper. In old cases, particularly in toe cracks, the 

 lun-n on the borders of the fissure loses its vitality and scales oil', 

 sometimes through the gi'eater i)art of its thickness, leaving behind 

 a rough and irregular channel extending from the coronet to the 

 end of the toe. 



In many cases of (piarter ciack. and in some cases of toe crack as 

 well, if the edges remain close together, with but little motion, the 

 fi.ssure is diy ; but in other cases a thin, offensive discharge issues from 

 the crack and the ulcerated soft tissues, or a fungusiil^e growth 

 protrudes from the narrow opening. 



When the cracks aie deep and the motion of their edges consider- 

 able, so that the soft tissues are Ijruised and i)in(hed with every 

 movement, a constant inflannnation of the parts is maintained and 

 the lauieness is severe. 



Oidinarily the lameness of .sand ciMck is slight when the i^atient 

 walks, but it is greatly aggravated ^\ hen he is made to trot, and the 

 harder the road the worse he limps. Furthernutre. the lauieness is 

 greatei- going downhill than up. for the reason that these conditions 

 are favorable to an increased motion in the edges of the fissure. 

 I^astly, more oi- less hemorrhage accomj)anies the iiueption of a sand 

 crack when the whole thickness of tiie wall is involved. Subsequent- 

 hemorrhages may also take place from fast work, jumjjing. or a 

 misstep. 



30444°— 16 2S 



