Lab mice provided with appropriate nesting materials are less likely to suffer “thermal stress”, which can negatively affect their welfare and skew the results of the research in which they are used, claims a new study.
Laboratory mice provided with appropriate nesting materials are less likely to suffer “thermal stress” that may negatively affect their welfare and skew the results of the research in which they are used.
Codes of practice and regulations used around the world specify temperature ranges in which to keep laboratory mice, usually in the range of 20-24°C. However, at these temperatures mice eat approximately 60% more than at their preferred temperature of 30°C in order to meet the energetic needs from increased metabolic demands.
This mild thermal stress can alter many aspects of physiology and behavior. According to the study, these alterations to normal physiology will alter scientific outcomes and have serious implications for animals meant to model human biological systems.
Lead researcher Joe Garner said: “If you want to design a drug that will help a patient in the hospital, you cannot reasonably do that in animals that are cold stressed and are compensating with an elevated metabolic rate.
“This will change all aspects of their physiology – such as how fast the liver breaks down a drug – which can’t help but increase the chance that a drug will behave differently in mice and in humans,” said Dr Garner
Rather than raising the temperatures in which the mice are kept (often not a feasible option), the study showed the importance of providing the mice with appropriate amounts and types of nesting materials with which the mice will themselves regulate their body temperatures to a comfortable level.
In the wild, mice cope with temperature extremes by building nests to minimise heat loss to the environment, so providing nesting material for mice to create microclimates within their cage (tailored to their thermal needs) would be an ideal solution to the problem of cold stress, the report claims.
- The paper “Heat or Insulation: Behavioral Titration of Mouse Preference for Warmth or Access to a Nest” is available to read in full at PLoSone.org.
- This research was funded by UFAW’s William Russell Memorial Fellowship.