Effects of Scruff Restraint and Handling—Tail and Tunnel—on Plasma Corticosterone in Female BALB/c Mice (Mus musculus)

Tunnel handling is a widely recommended, less-aversive method for improving laboratory mouse welfare by reducing handling-induced anxiety. While its effects on behavioral tests and physiologic outcomes have been reported, little is known about its impact on stress responses to brief restraint procedures commonly used in daily health checks and experimental work. This study aimed to investigate whether tunnel or tail handling influences the physiologic stress response of mice following a brief scruff restraint. Female BALB/c mice were assigned to one of 4 groups combining 2 handling methods (tail or tunnel) with or without a 10-second scruff restraint. Both single and repeated restraint procedures were evaluated separately. Voluntary interaction with the handling device was used to assess the suitability of the handling method. Plasma corticosterone (pCORT) concentrations were measured 20 minutes after restraint to evaluate the physiologic stress response. Tunnel-handled mice showed longer voluntary interaction times than tail-handled mice, indicating reduced handling aversion. Scruff restraint increased pCORT concentrations in both tail- and tunnel-handled mice. However, the handling method did not significantly affect pCORT concentrations following either single or repeated restraint. These findings suggest that the handling method has minimal impact on physiologic stress following brief restraint, supporting the use of less-aversive handling techniques without concern for confounding stress effects.