Table 4.
Some underlying evidence for the importance of random housing and random outcome assessment
| Random housing | ||
|---|---|---|
| Lighting |
Light exposure varies with respect to rack location and position of cages within the rack |
[27,28] |
| |
Small differences in light intensity have been associated with reproductive and behavioral changes |
[27,29,30] |
| |
There can be a four-fold difference in light intensity between cages at the top or bottom of a rack |
[18] |
| Temperature |
Temperature in animal room at 1.5 m can be 3-4˚C higher than at 0.5 m |
[18] |
| |
Cage temperature varies with group size |
[18] |
| |
Cage temperature varies with height of placement within the rack (top rack 5˚C warmer than bottom rack) |
[18,31,32] |
| |
Small changes in temperature can influence metabolic rates and toxicity |
[27,31,33] |
|
Random outcome assessment | ||
| Circadian rhythm | Periodic/circadian variations in lipid metabolism, neurotransmitter levels, pharmacokinetic effects, etc. | [34-37] |