Abstract: An apparatus and method useful for the removal of a mass of tissue from an animal which includes an elongated instrument, such as a needle, with a sheath device having a sleeve for treatment fluid delivery at the area of operation. The needle can be vibrated at ultrasonic frequency, preferably in the lateral direction, and treatment fluid, along with reduced pieces of tissue mass, can be removed from the area of treatment by means of aspiration through a conduit in the needle.