Table 2.

Key concepts relevant to changing housing conditions for research animals

1	Providing adequate animal care may not require EE, nor does provision of EE necessarily improve animal wellbeing.
2	Animals’ environmental preferences are not a guideline to their wellbeing and can be physically detrimental.
3	In many cases, neither laboratory animal science experts nor researchers can be certain whether altering a standard rodent environment compromises animal wellbeing or research results. When either outcome is in question, EE should not be mandated by the institution or oversight agencies.
4	Alterations in housing that clearly promote better health, reproduction, and fitness benefit both the animals and those who use and care for them. However, attempting to improve emotional states that cannot be reliably identified or measured may not benefit or may harm the animals or the research.
5	Variability can be difficult to control both within and between laboratories. The potential for small environmental differences to significantly affect research results should not be underestimated.

Adapted from reference 6.