, but considerable blemish is caused when sufficient irritation is
produced to stimulate resolution.

Vesication also is successfully employed in some instances. However,
only cases of recent origin in young animals--colts of two years or
younger--yield to blistering, and in some affected colts no doubt
recovery would have been spontaneous had no treatment been instituted.

Ligation of the saphenous vein at two points, one above and the other
below the distended ligamentous capsule, is an old operation, which has
undoubtedly given good results in some cases, although it does not seem
to be a rational procedure.

After-Care.--After swelling has fully developed--which occurs within a
week--the subject is turned to pasture and no attention is necessary
thereafter. A gradual subsidence of the swelling occurs and in the
average instance, this completely resolves within six or eight weeks.

Complete recovery succeeds the aspiration-and-injection-treatment in
about seventy-five per cent of cases as the result of one operation, and
subjects may be gradually and carefully returned to work in about sixty
days after treatment has been given.

Distension of the Tarsal Sheath of the Deep Digital Flexor.
(Thoroughpin.)

The terms "thoroughpin" or "throughpin" are translations from the French
_vessignon cheville_ and have the same significance. They are so named
because of the diametrically opposed distensions of the sheath of the
deep flexor tendon in such manner that the distensions appear to be due
to a supporting peg.

Anatomy.--The theca through which the deep digital flexor (perforans)
plays in the tarsal region, begins about three inches above the inner
tibial malleolus and extends about one-fourth of the way down the
metatarsus. The posterior part of the capsular ligament of the hock
joint is very thick in its most dependent portions and is in part
cartilaginous, forming a suitable groove for the passage of the deep
flexor tendon.

[Illustration: Fig. 57--Thoroughpin. Showing distension of the sheath of
the deep flexor tendon as it protrudes antero-externally to the fibular
tarsal bone (calcaneum).]

Etiology and Occurrence.--Strains and sequellae to debilitating
diseases constitute the usual causes of this affection. As a result of
acute synovitis a chronic synovial distension of the tarsal sheath
occurs. Bog spavin is often present in case of thoroughpin but the two
conditions are separate and distinct excepting