A Low-Stress, Long-Duration Stable Tail Vein Catheterization and Precise Drug Delivery Protocol for Awake, Freely Moving Mice.

Tail vein catheterization in mice is a standard technique for precise drug delivery in pharmacological research, offering high accuracy and reproducibility. However, existing techniques face significant limitations in maintaining long-term stable catheter patency in awake, freely moving mice, and there is currently no standardized, detailed protocol for tail vein catheterization. Current methods suffer from high rates of catheter dislodgement, increased animal stress from repeated injections, and movement restrictions, all of which introduce confounding variables in behavioral and pharmacological studies. We have developed a simple and efficient fixation method that maintains stable tail vein catheter patency for more than 60 min while allowing complete freedom of movement. This protocol employs a strain relief loop design and multi-point fixation strategy, effectively preventing catheter dislodgement during extended periods while minimizing animal stress. This protocol has been successfully applied across multiple research areas, including metabolic studies, behavioral assessments, and neuropharmacological research in awake mice, achieving >95% catheter retention with normal animal behavior, providing a reliable technical platform for long-term awake-state research applications. Key features • Maintains catheter stability for over 60 min in freely moving awake mice without physical restraint. • Catheter placement accommodates natural mouse behaviors (grooming, walking, standing). • Compatible with swivel systems for continuous drug infusion during behavioral testing. • Applicable to diverse research applications (metabolic studies, behavioral assessments, neuropharmacological research).