An applicator to apply a medication in liquid form to the skin or fleece of an animal. The applicator his a handle to be gripped by a user to move the applicator over the skin or fleece. Rotatably supported by the handle is a roller which is equipped with a cam track. Received within the cam track is a cam follower which causes reciprocation of a piston within a cylinder. The cylinder and piston co-operate to pump the liquid to a nozzle so that application of the liquid is metered in accordance with rotation of the roller.