A hand held injector for injecting fluids from a syringe into an animal subject comprising: a powerhead comprising: an injector housing; a drive ram bidirectionally movable in a first ram direction and a second ram direction along a longitudinal axis of said drive ram, said first ram direction corresponding with a fluid discharge direction; a motor drivingly coupled to said drive ram to selectively advance and retract said drive ram along said longitudinal axis; a plurality of buttons used to control operation of said powerhead; and a trigger mounted on a pivot of said injector housing, said trigger being movable to be displaced in first and second trigger directions; wherein pushing on a front portion of said trigger in said first trigger direction generates a control signal for said motor such that said drive ram moves along said longitudinal axis in said first ram direction, wherein pushing on a rear portion of said trigger in said second trigger direction generates another said control signal for said motor such that said drive ram moves along said longitudinal axis in said second ram direction, characterized in that. said trigger has a series of magnets associated therewith, wherein said injector further includes a trigger control signal sensor, said sensor adapted to detect a magnet of said series of magnets, and wherein said trigger control signals are wirelessly delivered from said trigger to said motor via a magnet. a powerhead comprising: an injector housing; a drive ram bidirectionally movable in a first ram direction and a second ram direction along a longitudinal axis of said drive ram, said first ram direction corresponding with a fluid discharge direction; a motor drivingly coupled to said drive ram to selectively advance and retract said drive ram along said longitudinal axis; a plurality of buttons used to control operation of said powerhead; and a trigger mounted on a pivot of said injector housing, said trigger being movable to be displaced in first and second trigger directions; wherein pushing on a front portion of said trigger in said first trigger direction generates a control signal for said motor such that said drive ram moves along said longitudinal axis in said first ram direction, wherein pushing on a rear portion of said trigger in said second trigger direction generates another said control signal for said motor such that said drive ram moves along said longitudinal axis in said second ram direction, an injector housing; a drive ram bidirectionally movable in a first ram direction and a second ram direction along a longitudinal axis of said drive ram, said first ram direction corresponding with a fluid discharge direction; a motor drivingly coupled to said drive ram to selectively advance and retract said drive ram along said longitudinal axis; a plurality of buttons used to control operation of said powerhead; and a trigger mounted on a pivot of said injector housing, said trigger being movable to be displaced in first and second trigger directions; wherein pushing on a front portion of said trigger in said first trigger direction generates a control signal for said motor such that said drive ram moves along said longitudinal axis in said first ram direction, wherein pushing on a rear portion of said trigger in said second trigger direction generates another said control signal for said motor such that said drive ram moves along said longitudinal axis in said second ram direction,