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NC3Rs: National Centre for the Replacement Refinement & Reduction of Animals in Research

Evaluating environmental enrichment

Supporting technicians in assessing the welfare impact of new enrichment.
Three brown mice inside, on top of and around a cubic wooden shelter with circular holes.

This resource compiled by the NC3Rs, RSPCA and Institute of Animal Technology (IAT) aims to help laboratory animals technicians make informed decisions about the suitability of environmental enrichment items for animals within their facility. A key aim is to empower technical staff to undertake robust evaluations of environmental enrichment items and assess their impact on animal welfare.

Example enrichment study protocols are provided for different levels of staff resource and expertise. The examples focus on mouse, rat and zebrafish husbandry; however the general advice (e.g. on experimental design) is applicable across all species.

The content has been developed for animal technicians, with practicality in mind. It is not intended to provide detailed guidance on ethology and experimental design for those working outside of research animal facilities.

Feedback and suggestions are welcome – email to get in touch.

On this page

What is environmental enrichment?

The term environmental enrichment can refer to any objects or general practices that enhance the level of physical, mental or social stimulation for captive animals. Good environmental enrichment improves the quality of life for animals by enabling them to carry out natural (species-typical) and desirable behaviours, providing cognitive challenges and opportunities to make choices and have a degree of control over the environment.

A more stimulating environment can be achieved through adapting cage size, design or contents. Equally as important is considering the quality and quantity of social stimulation, with an understanding that, for some species, social enrichment can come from both other animals and human handlers.

Why do we need to evaluate environmental enrichment?

Environmental enrichment needs to be suitable for the species, strain and individuals in question. Unsuitable enrichment items can, at best, go unused or, at worst, cause direct harm to the animals involved (e.g. by causing injury or increasing aggression). Conversely, enrichment that meets the needs of research animals can reduce their stress levels and make them calmer and easier to handle, ultimately improving data quality and benefiting the science. Many new enrichment products reach the market without any prior evaluation of their success in improving animal welfare. 

Taking a science-based approach to evaluating enrichment items will allow you to demonstrate their suitability and effectiveness for the animals in your care. Many animal technicians will have a feeling of what kinds of enrichment might be appropriate and effective, but it is in the best interests of the animals and the facility management to back this up with robust data from repeated observations. Enrichment can be time consuming to provide; therefore, it is important for technicians to know that their limited time is not wasted on ineffective enrichment.

Barriers to evaluating environmental enrichment

Most animal technicians appreciate the importance of providing a high quality environment for their animals, but may encounter barriers that prevent them from evaluating enrichment using a scientific approach, some of which are discussed in an NC3Rs blog post. This resource has been designed with these constraints in mind, including a designated section addressing common concerns and FAQs

How to use this resource

  • Read through all sections to familiarise yourself with suitable enrichment for the laboratory animal species you work with and how to evaluate whether your chosen enrichment items will effectively improve animal welfare.
  • Use the example protocols and other guidance on our approaches to evaluating enrichment page to plan your own enrichment evaluation study. In particular, the decision table will help you decide what type of study protocol might best suit your circumstances, taking account of the time investment and resources required. We also provide advice on adapting the protocols and improving the scientific quality of your study.
  • Before you begin your study, consider the preparation required and the steps that follow on from data collection (i.e. data analysis and sharing your findings).

Additional resources

We gratefully acknowledge all contributors to this resource, especially Dr Penny Hawkins of the RSPCA’s Animals in Science Department, the Animal Welfare Group of the IAT, and technicians from the University College London’s Welfare Trials Group. We are also grateful to the units, technicians and researchers who contributed images for use in this resource, including those whose images are used for the banner at the top of this page: University College London, the Preclinical Research Facility at the University of Leicester and the University of Cambridge.