DISEASES OF THE FETLOCK, ANKLE, AND FOOT. 433 
Fast work on hard roads, jumping, and blows on the coronet, 
together with calk wounds of the feet, are accidental causes of quar- 
ter cracks in particular. Toe cracks are more likely to ce caused by 
heavy pulling on slippery roads and pavements or on steep hills. 
Symptoms.—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 mud, ointments, tar, wax, putty, gutta-percha, 
or by the long hairs of the coronet. 
Sand cracks sometimes commence on the internal face of the wall, 
involving its whole thickness excepting a thin layer on the outer 
surface. In these cases the existence of the injury may be suspected 
from a slight depression,which begins near the coronary band and 
follows the direction 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 quar- 
ter crack the opposition is true; the fissure closes when the weight is 
removed from the foot. Asa 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 cracks, the 
horn on the borders of the fissure loses-its vitality and scales off, 
sometimes through the greater part of its thickness, 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 funguslike growth 
protrudes from the narrow opening. 
When the cracks are deep and the motion of their edges consider- 
able, 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 ig 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 downhill than up, for the reason that these conditions 
are favorable to an increased motion in the edges of the fissure. 
Lastly, more or less hemorrhage accompanies the inception of a sand 
crack when the whole thickness of the wall is involved. Subsequent 
hemorrhages may also take place from fast work, jumping, or a 
misstep. 
36444°—16——28 
