Large-scale mouse phenotyping programs generate valuable biological knowledge but create welfare challenges from the volume of procedures and the management of large mouse populations.
Mouse phenotyping programs represent a welfare challenge of scale: each individual mouse may undergo relatively modest procedures, but multiplied across thousands of animals, the cumulative welfare impact is substantial. The industrialization of biological research creates pressure toward efficiency that can work against careful individual welfare monitoring. Refining phenotyping pipelines to reduce procedure severity, improving monitoring systems that detect welfare problems promptly in large populations, and applying humane endpoint criteria consistently across high-throughput settings are essential welfare obligations for these programs. The scientific value of systematic phenotyping is real and important, but it does not reduce the welfare obligations to individual animals.