SPAVIN

[from the Old French espavent]: Any swelling or abnormal growth in or on the hock. A "bog spavin" is a soft swelling on the medial and/or dorsal surface of the hock. A "blood spavin" is an enlarged vein, and a harmless blemish. A "bone spavin" is an exostosis on any of the tarsal bones. Large bone spavins are called "jack spavins". "Blind" or "occult spavins" are exostosises not visible on the exterior of the hock.