An injector for injecting fluids from a syringe into an animal subject comprising: a drive ram bidirectionally movable along a longitudinal axis of said drive ram; a motor drivingly coupled to said drive ram to selectively advance and retract said drive ram along said longitudinal axis; and a syringe mount engageable with a syringe to position said syringe relative to said injector to permit said drive ram to engage and move a plunger within said syringe; wherein said syringe mount includes first and second pivotable members (92, 94) each pivotable toward the other, and toward and away from the longitudinal axis of symmetry of said drive ram such that said first and second members may be placed in an open position and a closed position; and characterized in that: the injector further comprises a powerhead including a sensor for detecting when the user opens and closes the syringe mount; and in that the injector includes powerhead software configured to enter an enabled state for the injector upon detection of a sequence including the following steps: the sensor detects that a user opens and closes the syringe mount when the drive ram is in a home position; the powerhead software verifies that all injection start signals are inactive; and the user purges a minimum of 1ml with a purge/retract trigger of the injector and then releases the purge/retract trigger. a drive ram bidirectionally movable along a longitudinal axis of said drive ram; a motor drivingly coupled to said drive ram to selectively advance and retract said drive ram along said longitudinal axis; and a syringe mount engageable with a syringe to position said syringe relative to said injector to permit said drive ram to engage and move a plunger within said syringe; wherein said syringe mount includes first and second pivotable members (92, 94) each pivotable toward the other, and toward and away from the longitudinal axis of symmetry of said drive ram such that said first and second members may be placed in an open position and a closed position; and characterized in that: the injector further comprises a powerhead including a sensor for detecting when the user opens and closes the syringe mount; and in that the injector includes powerhead software configured to enter an enabled state for the injector upon detection of a sequence including the following steps: the sensor detects that a user opens and closes the syringe mount when the drive ram is in a home position; the powerhead software verifies that all injection start signals are inactive; and the user purges a minimum of 1ml with a purge/retract trigger of the injector and then releases the purge/retract trigger. the injector further comprises a powerhead including a sensor for detecting when the user opens and closes the syringe mount; and in that the injector includes powerhead software configured to enter an enabled state for the injector upon detection of a sequence including the following steps: the sensor detects that a user opens and closes the syringe mount when the drive ram is in a home position; the powerhead software verifies that all injection start signals are inactive; and the user purges a minimum of 1ml with a purge/retract trigger of the injector and then releases the purge/retract trigger. the sensor detects that a user opens and closes the syringe mount when the drive ram is in a home position; the powerhead software verifies that all injection start signals are inactive; and the user purges a minimum of 1ml with a purge/retract trigger of the injector and then releases the purge/retract trigger.