Danner, L., Rao, V. P. 2017. Should rat enrichment devices be used beyond a month? Laboratory Animal Science Professional 5(1) (March), 41-43.

Enrichment devices made of materials such as nylon and wood are common gnawing devices used in animal facilities. In most institutions, these devices are used for a limited period and then discarded. At Pfizer, enrichment devices are typically used for 4 weeks and discarded. We hypothesized that the enrichment devices when retained and reused in clean cages for longer periods may provide olfactory cues that are beneficial to rats. However, we wanted to determine if the enrichment devices are safe to the animals when used beyond the 4-week period. Since animal saliva, urine, feces, and microorganisms are likely to accumulate to higher levels on these devices when left in cages for extended periods, we wanted to test if enrichment devices can be used safely for up to 12 weeks and whether this change in practice will affect the health of the rats. W found that extending the duration of enrichment devices without cleaning them during cage change does not seem to have any untoward consequences to the health of the animals. Although we noticed an initial increase in enrichment device bacterial load and debris accumulation levels at week four, these levels dropped subsequently as rats continued to use them, suggesting that the devices when left for extended periods pose no greater risk to the health of the animals.