742 
DISEASES OF THE HOCK. 
Diagnosis. The examination for this enlargement is similar to that for 
spavin. The outer surfaces of the hocks should be compared. As a rule, 
it is easy to discover whether the skin alone is thickened, or whether the 
deeper-lying structures are involved. 
The prognosis is usually favourable. Only when spavin is also present 
is the prognosis doubtful. 
Treatment is usually unnecessary. If the ligaments and periosteum 
are acutely inflamed, they should be treated accordingly. In most cases 
rest and blistering remove the lameness, though thickening seldom dis¬ 
appears, and a slight blemish may always remain. 
VII.—CURB. 
In horsemen’s parlance, this name includes all swellings on the posterior 
surface of the hock-joint. Seen from one side, the back of the hock-joint 
should appear as an absolutely straight line, stretching from the tuber 
calcanei to the fetlock. About 8—4 inches below the point of the calcis 
a swelling or convexity sometimes appears. (The French “ courbe ” is 
not identical with the English curb.” It represents a bony enlargement 
on the inner surface of the lower extremity of the tibia.) 
In certain cases enlargements occur in and about this region, due to 
excessive development of the external small metatarsal, to thickening of 
the skin, or of the flexor pedis perforans or perforatus tendons, or to dis¬ 
tension of the bursa tendinea of the flexor pedis perforans, which lies at 
this point, and is connected with the calcano-cuboid ligament. These 
conditions, which are usually easy of recognition, must, however, be 
distinguished from curb, which results from thickening of the calcano- 
cuboid ligament (ligamentum tarsi plantare). The upper end of this 
ligament is attached to the posterior surface of the os calcis, whence it 
passes downwards, to become attached to the cuboid, to the external 
small metatarsal, and to the scaphoid, as well as to the large metatarsal. 
In consequence of sprain, it often becomes inflamed, and afterwards 
chronically thickened, or the inflammation may possibly induce changes 
m the joint itself. Thickening of the flexor pedis perforans tendon, and 
especially of its reinforcing ligament, is usually easy to differentiate from 
curb, inasmuch as it extends further downward, i.e., can be traced along 
the tendon itself. 
Causes. The lower portion of the limb, from the point of the os calcis 
to the giound, may he legaided as along lever. The pull of the gastroc¬ 
nemius muscles acting on the point of the calcis tends to break this lever 
in two across the fulcrum, represented by the lower end of the tibia. The 
tissue which resists the breaking strain and holds the os calcis in line 
with the other bones of the limb is the calcano-cuboid ligament. It is 
