How Do Individually Ventilated Cages Affect the Welfare of Male BALB/c Mice? Comprehensive Assessment of Behavior, Metabolism, and Responses to Acute Painful Stimuli.

INTRODUCTION: Housing conditions, which have a major impact on the welfare of laboratory animals, are an important issue in experimental research. Individually ventilated cage (IVC) and open-top cage (OTC) systems are widely used for housing laboratory mice. PURPOSE: This study aimed to comprehensively investigate the effects of OTC and IVC housing conditions on the behavior, metabolism, and pain responses of laboratory mice from an animal welfare perspective. METHOD: We measured body temperature, body weight, anxiety levels (using the elevated plus maze and open field test), and thermal nociceptive responses (using the hot-plate and tail-flick tests) in male albino BALB/c mice. At the end of these procedures, the mice were sacrificed, and the serum levels of adrenocorticotropic hormone (ACTH), corticosterone (CORT), ghrelin, and leptin were determined by ELISA, and the weight of the adrenal glands was measured. FINDINGS: The results showed that there were significant differences in body weight, body temperature, anxiety-related behaviors, pain latency, and hormonal parameters between the OTC group and the IVC group. Compared to OTC, IVC had lower levels of leptin, especially under stress conditions, where a significant interaction between housing and stress was observed, and higher levels of ghrelin, ACTH, and CORT. IVC group also had increased body weight, adrenal gland weight, and body temperature. In the hot-plate test, the IVC group showed increased latency of hind limb responses compared to the OTC group, but not in the tail-flick test. IVC group exhibited more anxiety-related behaviors in the OFT, while no differences were observed in the EPM. CONCLUSION: According to the results of this study, housing mice in IVCs appears to compromise welfare, altering behavioral, hormonal, and pain responses. This suggests that the IVC system can induce physiological and behavioral stress, potentially acting as a systemic confounding factor in mouse research.