Abstract: According to the present invention there is provided a castrating device comprising a first arm, a first jaw plate carried by the first arm, a second arm, a pivotal mounting for the second arm, a second jaw plate, means connecting the second jaw plate to the second arm for movement therewith, and means for guiding the second jaw plate so that, when it moves with the second arm, it does so along a rectilinear path towards and away from the first jaw plate, and means for displacing the pivotal mounting of the second arm to enable slackness to be taken up.The second arm can be pivotally mounted on a tensioning bar which extends longitudinally of the first arm.