Stereotypic behaviors in laboratory mice, including repetitive circling, bar-chewing, and route-tracing, are reliable welfare indicators of chronic stress and inadequate housing.
The presence of stereotypies in laboratory mice is a clear signal of chronic welfare compromise. These behaviors develop when animals are persistently prevented from performing highly motivated behaviors, most commonly burrowing, nesting, and escape. Once the neural pathways underlying stereotypy are established, they become permanent regardless of subsequent environmental improvements. This means that preventing stereotypy development through adequate housing from the outset is far more important than remediation. Laboratories with high stereotypy prevalence are effectively running chronic stress experiments on their control animals, both causing unnecessary suffering and compromising the scientific validity of research conducted in those animals.