Animal implantates may be removed by a knife that permits the insertion and removal of blades without the manipulation of fasteners. Such a knife may be inexpensively manufactured by molding two relatively simple pieces that can be fitted together to hold a scalpel blade and to permit its incision to be guided and limited in depth. One piece of such a knife forms a handle having a first portion adapted to be gripped by hand and a blade-carrying second portion forming two ribs with a central slot. The second piece is a blade carrier having a first side surface adapted to engage an opening in a blade to hold the blade in fixed position on the blade carrier. The blade carrier has an upper bearing surface adapted to engage a rib of the first handle portion and a surface projecting upwardly centrally of the bearing surface and being adapted to engage the ribs of the first portion. The blade carrier is assembled to the handle by inserting its upwardly projecting portion into the central slot of the handle where it is fixedly retained. When assembled, the two pieces hold the blade in position for use.