Traditional tail-lifting to pick up mice induces anxiety and aversion, causing handler-avoidance behavior that can confound downstream injections and behavioral testing.

Switch to non-aversive tunnel or cup handling to reduce handling stress: 1) Leave a handling tunnel in the home cage for at least 5 days so mice habituate to it; guide the mouse in with both ends open, then cup a hand over one end and tilt gently to move it. 2) Restrain by grasping the tail at the tunnel's base rather than lifting by the tail itself. 3) Expect new handlers to need a few days to a few weeks to gain proficiency, and post-weaning mice to need roughly 3 weeks before they are comfortable with cup handling. 4) Note strain differences: C57BL/6 mice tend to be more unsettled with hand-cupping and need more extensive habituation, while BALB/c, BALB.k, and outbred ICR (CD-1) mice habituate much faster and settle with either method. 5) Mice habituated to tunnel/cup handling tolerate subsequent scruff restraint for procedures far better than mice picked up by the tail.