New rules in the European Union directive for protecting laboratory animals call for a formal assessment of any pain that these animals might experience during scientific procedures (see go.nature.com/porg2x).

An upcoming workshop, organized by Germany's Federal Institute for Risk Assessment, will evaluate national guidelines on pain assessment drawn up in a similar workshop last year, with particular reference to 'harmful phenotypes' — animal lines that are likely to experience pain as a result of genetic alteration (see go.nature.com/8dhjcz).

Maintenance of such genetically altered animals, which carry the defining mutation at a single genetic locus, is currently subject to project authorization. This consent ensures that pain is monitored closely in these animals by veterinarians, animal-welfare officers, scientists and laboratory staff who are responsible for animal care. Breeding more animals for the purpose of assessing pain severity is not permitted, and neither is subjecting them to further pain — as inflicted, for example, by routine blood testing.

Participants in the next workshop, to be held in October, will collate experiences resulting from implementation of the 2013 guidelines and will develop a database for pain-assessment results from genetically altered animals.