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Changes to the ARC Policy on Environmental Enrichment are proposed as described in this Word document: Environmental Enrichment (draft). DLAM advises that most of the mouse enrichment practices described in this document have, in fact, been in effect for some time; however, your attention is drawn to a significant change in the proposed enrichment for rats:

All rats (socially-housed and singly-housed) will now receive physical enrichment in the form of paper twists that they can tear up, make nests with, etc. (Currently socially-housed rats receive no physical enrichment items and singly-housed rats receive a Nylabone).

You are invited to comment on these proposed changes in the next 30 days, prior to final Policy approval by the ARC and subsequent implementation by DLAM, by contacting the ARC. All suggestions will be considered by the ARC and additional Policy revisions made as appropriate.

Should your concerns be purely about the timing of any resulting changes impacting your current experiments, rest assured that DLAM will work with you to delay implementation for your animals until such time as this is no longer an issue.

As is currently the case, scientific justification for exceptions to provision of environmental enrichment, more generally, must be described in an approved ARC protocol.

The following literature is provided for your edification on the topic of enrichment – both its benefits to animal welfare and its potential to impact the outcome of experiments. Again, the ARC welcomes your comments and referrals to additional literature.

Nigel T. Maidment, Ph.D.
Chair, ARC

Eric Hutchinson, Anne Avery, Sue VandeWoude; Environmental Enrichment for Laboratory Rodents, ILAR Journal, Volume 46, Issue 2, 1 January 2005, Pages 148–161.

Toth, L. A., Kregel, K., Leon, L., & Musch, T. I. (2011). Environmental Enrichment of Laboratory Rodents: The Answer Depends on the Question. Comparative Medicine, 61(4), 314–321.

Wurbel H & Garner JP (2007). Refinement of rodent research through environmental enrichment and systematic randomization.

Wurbel H (2007). Environmental enrichment does not disrupt standardization of animal experiments.

Wolfer DP et al. (2004). Laboratory animal welfare: cage enrichment and mouse behavior. Nature 432: 821-2. PMID: 15602544

Benefiel AC et al. (2005). Mandatory “enriched” housing of laboratory animals: the need for evidence-based evaluation. ILAR J 46:95-105 PMID: 15775019.

Tsai PP et al. (2003). Are the effects of different enrichment designs on the physiology and behavior of DBA/2 mice consistent? Laboratory Animals 37:314-327. PMID: 14599306

Van Praag H et al. (2000). Neural consequences of environmental enrichment. Nat. Rev. Neurosci. 1:191-198. PMID: 11257907.

Bayne K (2005). Potential for unintended consequences of environmental enrichment for laboratory animals and research results. ILAR J 46:129-139. PMID: 15775022

Eskola S et al. (1999). Environmental enrichment may increase the number of rats needed to achieve statistical significance. Scandanavian J. Animal Science 26:134-44.

Watson, D. Evaluation of inanimate objects on commonly monitored variables in preclinical safety studies for mice and rats. Lab Anim. Sci. 43, 378–380 (1993).

Froberg-Fejko K (2014) Give a rat a bone: satisfying rodents’ need to gnaw. Lab Animal 43, 378–379.

Hullinger R, O’Riordan K, Burger C. Environmental enrichment improves learning and memory and long-term potentiation in young adult rats through a mechanism requiring mGluR5 signaling and sustained activation of p70s6k. Neurobiol Learn Mem. 2015 Nov;125:126-34. doi: 10.1016/j.nlm.2015.08.006. Epub 2015 Sep 2.

Jacqmain J, Nudi ET, Fluharty S, Smith JS. Pre and post-injury environmental enrichment effects functional recovery following medial frontal cortical contusion injury in rats. Behav Brain Res. 2014 Dec 15;275:201-11. doi: 10.1016/j.bbr.2014.08.056. Epub 2014 Sep 6.

Hamilton KR, Elliott BM, Berger SS, Grunberg NE. Environmental enrichment attenuates nicotine behavioral sensitization in male and female rats. Exp Clin Psychopharmacol. 2014 Aug;22(4):356-63. doi: 10.1037/a0037205. Epub 2014 Jun 23.

Pamidi N, Nayak BS, Mohandas KG, Rao SS, Madhav NV. Environmental enrichment exposure restrains the neuronal damage induced by diabetes and stress in the motor cortex of rat brain. Bratisl Lek Listy. 2014;115(4):197-202.

Jenks KR, Lucas MM, Duffy BA, Robbins AA, Gimi B, Barry JM, Scott RC. Enrichment and training improve cognition in rats with cortical malformations. PLoS One. 2013 Dec 17;8(12):e84492. doi: 10.1371/journal.pone.0084492. eCollection 2013.

Hannan AJ. Environmental enrichment and brain repair: harnessing the therapeutic effects of cognitive stimulation and physical activity to enhance experience-dependent plasticity. Neuropathol Appl Neurobiol. 2014 Feb;40(1):13-25. doi: 10.1111/nan.12102. Review.

Pang TY, Hannan AJ. Enhancement of cognitive function in models of brain disease through environmental enrichment and physical activity. Neuropharmacology. 2013 Jan;64:515-28. doi: 10.1016/j.neuropharm.2012.06.029. Epub 2012 Jul 2. Review. Erratum in: Neuropharmacology. 2013 Feb;65:20.