Home Office ministers have accepted the Animals in Science Committee’s advice to conduct a themed audit of how cumulative severity is considered in project licences authorising severe procedures on non-human primates. The acceptance, set out in correspondence published on 28 October 2025, confirms the Animals in Science Regulation Unit (ASRU) will begin the work in 2026.
The ASC’s letter of 18 August 2025 followed two licence review meetings on 1 August that raised recurring questions about how actual severity is determined and how lifetime burden is accounted for in licences authorising severe procedures on non-human primates. The Committee recommended an ASRU‑led themed audit to quality assure these processes and to inform improved guidance and the sharing of practice between establishments.
Responding on 1 October 2025, Lord Hanson of Flint, Minister of State at the Home Office, accepted the recommendation and asked officials to work with the Committee on implementation. He noted ASRU is concluding a regulatory reform programme and indicated that the Head of the Regulator will set the timetable, with commencement expected in 2026.
Under the Animals (Scientific Procedures) Act 1986, severity is classified prospectively and reported retrospectively as non‑recovery, mild, moderate or severe. Actual severity must reflect the highest level experienced by an individual animal, including cumulative effects across procedures within a project, and Animal Welfare and Ethical Review Bodies (AWERBs) are required to follow projects and promote the 3Rs.
For licence holders and AWERBs overseeing non-human primate work authorised at the severe limit, the audit focus signals closer scrutiny of retrospective assessment records, the rationale for severity judgements, and how cumulative burden is documented and mitigated. Establishments should be prepared to evidence decision‑making, humane end points and how learning is embedded into refinements across the life of the project.
This development sits alongside the Home Office decision published on 15 September 2025 to accept all ASC recommendations on the breeding and supply of non‑human primates. New authorisations require animals from self‑sustaining colonies or second‑generation captive‑bred stock, with a time‑limited transition for cynomolgus macaques until 1 August 2026.
ASRU’s broader licensing reforms have progressed over the year. In March 2025 the Animals in Science Regulation Policy Unit set out changes to tighten guidance in the e‑licensing system and require additional justification where non‑animal methods exist, indicating a stronger emphasis on evidence in applications and oversight.
The immediate change is confined to commissioning the themed audit; existing licence conditions under A(SP)A remain in force. The minister agreed that a deeper understanding of retrospective assessment would provide a foundation for improved guidance and sharing of best practice, with ASRU to engage the ASC as audit scope and timing are finalised in 2026.