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.
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 in that both may occur simultaneously and as the result of the same cause. Some animals are undoubtedly predisposed to disease of synovial structures. The average horse that has been subjected to hard service on pavements or hard roads at fast work suffers synovial distension of bursae, thecae or of joint capsules. Some of the well bred types such as the thoroughbred horses may be subjected to years of hard service and still remain “clean limbed” and free from all blemishes. Thus it seems that subjects of rather faulty conformation, animals having lymphatic temperaments and the coarse-bred types, are prone to synovial disturbances such as thoroughpin, bog spavin, etc., sometimes having both legs affected.
[Illustration: Fig. 58—Fibrosity of tarsus as a complication in chronic thoroughpin.]