Changes in the sustentaculum tali associated with distension of the tarsal sheath (thoroughpin)

Results of the clinical and radiographic examination of 8 lame horses with tarsal sheath distension are described. In chronic cases pathological exostoses were identified radiographically in the sustentaculum tali and were demonstrated at post mortem in 4 of the horses which were destroyed. The prognosis and the feasibility of treatment are discussed in the light of these changes and the associated damage found at post mortem in the deep flexor tendon and its sheath. Trauma to the hock was known to have occurred in half the cases and was suspected in the others.