Rheumatoid arthritis in mice

A pharmaceutical company introduced the G6PI, CIA and CAIA mouse models of rheumatoid arthritis, which have the potential to cause severe suffering. This prompted a re-evaluation of the company's welfare scoring sheets and husbandry refinement protocols, with the aim of reducing suffering. The researchers, animal technologists and Named Animal Care and Welfare Officer worked together to tailor and refine monitoring systems, husbandry and procedures.

Mice used in G6PI and CAIA studies were very carefully monitored by researchers and technologists, to identify indicators of adverse effects and collate data on weight loss and disease scores. The observations were specific to each model, although standardised terminology was created to describe indicators. As a result, the following refinements were adopted:

  • the humane endpoint for weight loss was reduced from 25 per cent to 20 per cent, and another endpoint added of a 15 per cent weight loss that persisted for 5 days;
  • the tailored indicators (such as soft stools for CAIA) enabled study length to be reduced; e.g. the CIA studies were reduced from 30 days to 20;
  • disease scores were revised to include a range of indicators, as opposed to paw volume only, capturing severity more effectively and enabling endpoints to be further refined;
  • additional refuges are provided for DBA/1 male mice, eliminating aggression;
  • non-tangling nesting material is provided;
  • when mobility is restricted, longer sipper nozzles are fitted and food given in dishes on the cage floor;
  • the Mouse Grimace Scale is used to help assess acute pain.