Well-being in Mice

13 The assessment of pain, distress and suffering, as well as evaluation of the efficacy of stress14 reduction strategies, is crucial in animal experimentation but can be challenging in laboratory 15 mice. Nest building and burrowing performance, observed in the home cage, have proved to 16 be valuable and easy-to-use tools to assess brain damage or malfunction as well as 17 neurodegenerative diseases. Both behaviors are used as parameters in models of psychiatric 18 disorders or to monitor sickness behavior following infection. Their use has been proposed in 19 more realistic and clinically relevant preclinical models of disease, and reduction of these 20 behaviors seems to be especially useful as an early sign of dysfunction and to monitor disease 21 progression. Finally, both behaviors are reduced by pain and stress. Therefore, in combination 22 with specific disease markers, changes in nest building and burrowing performance may help 23 provide a global picture of a mouse`s state, and thus aid monitoring to ensure well-being in 24 animal experimentation. 25