Restriction of the tarsal sheath while in motion leads to thoroughpin.

Horses with sickle-hocks are at an increased risk of developing thoroughpin, curb and bog or bone spavins.

Thoroughpin - Thoroughpin is the swelling of the deep digital flexor tendon sheath.

Closed angulation and loading on the back of the hock predisposes the horse to bone and bog spavin, thoroughpin, and curb.

James Keene was not initially enthusiastic about Colin, noting his disfiguring curb, or thoroughpin, meaning that the colt had an enlarged hock.

Stress to the tendon from over work or over extension, trauma to the tendon and joint, or poor conformation of the hock joint can cause thoroughpin.

Hoof swings in as the horse picks up its hocks and then rotates out, predisposing the animal to interference and causing excess stress on lateral hock structures, predisposing the horse to bog and bone spavin, and thoroughpin.