Identifying individual laboratory animals is essential for research integrity and welfare monitoring, but common identification methods vary considerably in the welfare costs they impose.
Animal identification methods represent a welfare decision that is often made without sufficient attention to the alternatives. Neonatal toe clipping for genotyping, while providing tissue for DNA analysis, causes acute pain that is often administered without analgesia on the assumption that neonates do not feel pain. The evidence does not support this assumption. Ear tags cause ongoing irritation and occasional infection. Each of these welfare costs is incurred millions of times annually across the global laboratory animal population. Advances in non-invasive identification through computerized recognition of natural markings, whisker patterns, and RFID technology are making it increasingly possible to identify animals without physical marking, providing an achievable welfare improvement.