The tarsal sheath is a relatively large structure and has an exposed position on the medial aspect of the hock in horses. Because of that, it may be affected by various diseases. The precise knowledge of anatomical location, extend and relationship to surrounding structures and diagnostic modalities is an important prerequisite to diagnose those conditions. The goal of the present study was to illustrate and document the anatomical details in cadaver limbs. Furthermore, a retrospective analysis of all cases with tarsal sheath involvement pre- sented to the Large Animal Clinic for Surgery, Faculty of Veterinary Medicine, University of Leipzig in a seven year period (2005-2011) was performed. A detailed anatomical description of the tarsal sheath based on our own evaluation as well as literature findings is presented. It was noted that the description of the anatomical situation in the present literature is neither consistent, nor precise and partly outdated. Among patients presented to our hospital, diseases of the tarsal sheath have a low incidence (0.3 %). Based on the clinical findings, most cases could be allocated to one of four groups: 1) acute to chronic, subclinical aseptic tenosynovitis, 2) chronic, clinical apparent, asep- tic tenosynovitis, 3) acute, septic tenosynovitis due to laceration, and 4) acute tenosynovitis secondary due to cellulitis. Some conditions warrant immediate and comprehensive treatment whereas other conditions have a low clinical relevance and may heal on their own. Prognoses for life, for full athletic function as well as cosmetic appearance of the hock vary considerably among the diseases affecting the tarsal sheath.