Haussman, Haussman-Dunn gag
a speculum for examining the mouth cavity of cattle and sheep. Two horizontal plates accommodate the upper and lower dental arcades (upper dental pad in cattle). They are carried on ratcheted scissor-type mechanisms supported up each side of the face by a poll strap. When levered open the plates stay open until the ratchet is released. Gives excellent access to the mouth but excludes incisor teeth.