to the front and outside of the stifle and the application repeated in two
or three weeks.

STRING-HALT.--This term is applied to a peculiar involuntary movement of
one or both hind limbs that is characterized by a sudden, purposeless
flexion of the hock-joint (Fig. 45). Horses that are slightly affected may
show this movement of the hind limbs when first exercised. Other horses may
be "string-halted" when backed, turned, walked, or trotted, and fail to
drive out of it. The cause of true "string-halt" is not known.

_The treatment recommended is surgical._ This consists in cutting the
tendon of the peroneus muscle. The seat of the operation is a little below
the hock and on the external face of the cannon.

[Illustration: FIG. 45.--String-halt.]

SPAVIN.--A spavin is a chronic inflammation of the articular faces of the
hock bones, ligaments and synovial membranes. The inflammation may result
in the formation of a bony enlargement on the inner surface of the region,
and a union between the small bones forming the lower portion of the hock,
and the upper extremities of cannon and lower hock bones (Figs. 46 and 47).

[Illustration: FIG. 46.--A large bone spavin.]

The _predisposing causes_ are of the greatest importance. A spavin is one
of the unsoundnesses of horses that may be transmitted to the offspring.
Young colts that have heavy bodies and are fed a fattening ration are
predisposed to it. Crooked hind limbs, small hocks and quarters that are
heavily muscled are predisposing factors. The _external causes_ are strains
caused by slipping, turning quickly, rearing, pulling heavy loads and