1. Service Units
  2. Research Integrity & Compliance
  3. Animal Research
  4. Institutional Animal Care and Use Committee (IACUC)
  5. IACUC Approved Policies
  6. Animal Housing and Enrichment
  • uconn health
Page content relevant to:

Animal Housing and Enrichment

Purpose

The Public health Service (PHS) policy on Humane and Care and Use of Laboratory animals endorses US Government principles on use of Vertebrate Animals used in Testing, Research and Training, principle VII – ‘The living conditions of animals should be appropriate for their species and contribute to their health and comfort. Based upon this Guide for the Care and Use of Laboratory Animals emphasizes “that animals should be housed with a goal of maximizing species-specific behavior and minimizing stress induced behavior.

The primary aim of environmental enrichment is to enhance animal well-being by providing animals with sensory and motor stimulation, through structures and resources that facilitate the expression of species specific behavior and promote psychological well-being through physical exercise, manipulative activities, and cognitive challenges according to their species specific characteristics.

The environmental enrichment should be biologically relevant (i.e. hiding, gnawing, socializing, foraging, searching) so that is does not lose its enriching value over time. Environmental enrichment via physical manipulanda, structure, or substrate is preferred over nutritional enrichment.

All principal investigators working with laboratory animal are required to allow animal enrichment unless there is scientific justification against the use of enrichment as approved by the Institutional Animal Care and Use Committee (IACUC).  The justification must be included in an IACUC protocol submission and approved by the Attending Veterinarian and the IACUC.

Introduction of novel enrichment materials must be approved by the investigator and the Attending Veterinarian before introduction.

Definitions

Physical manipulanda are non-nutritive objects that can be altered by the animal or encourage fine motor movements. These include plastic/nylon, wood block chew toys – the preferred standard method of rodent enrichment at CCM.

Manipulanda are sanitized at least as frequently as the animal’s primary enclosure (cage)

Structure and substrate includes objects that allow an animal to isolate itself into different microenvironments, experience varied textures or materials. These include nesting materials, running wheels and hiding shelters.

Structure and substrate are replaced or sanitized at least as frequently as the animal’s primary enclosure (cage).

Nutritional enrichment may be provided in lieu of physical manipulanda, structure or substrate if necessary for research purposes.

Nutritional enrichment is accomplished by provision of novel foods or provision of small pieces of the normal diet in the bedding to stimulate foraging.

Procedure

Included in this are the Veterinarian Recommended Enrichment used currently at the CCM animal colony.

In addition, sometimes animals must be singly-housed due to various reasons such as incompatibility, pregnancy, surgery, medical isolation and other veterinary related issues.

Mice

  • Social Housing: Animals are group housed whenever possible. Male mice may be housed singly due to their aggressive nature.

On occasions, mice may be singly housed due to study requirements (vasectomized males in breeding studies, surgeries), social incompatibility/fighting, or clinical reasons.

If mice are singly housed, they will be provided with 2 enrichment materials (e.g,, igloos and nestlets).

  • Shelter: Nesting materials (e.g. Nestlets™); Igloos, shepherd shacks, cardboard tubes, and taper cups
  • Other: Chew blocks, Nylabones™

Rats

  • Social Housing: Animals are group housed whenever possible. Male rats may be housed singly due to their aggressive nature.
  • Shelter: Tubes (polycarbonate); Nesting materials may be desirable for dams nearing parturition and during lactation.
  • Other: Nylabones™

Rabbits

Most rabbits housed in CCM animal facility are typically male rabbits and are used for surgical studies.

  • Social Housing:
    1. All male rabbits are singly housed
    2. All rabbits (male and female) in surgical studies are singly housed.
    3. If female rabbits are used for non-surgical studies, efforts will be made to socially house them. That may include housing together in the same cage, or with open divider between the rack for the rabbits to socialize.
    4. If female rabbits need to be singly housed for research purposes, appropriate scientific justification must be given, reviewed and approved in the IACUC protocol
  • Environmental Enrichment: Elevated shelves, Cardboard boxes, toys (balls, bells, etc.)
  • Dietary Items: Food items (e.g., alfalfa cubes/timothy hay/lettuce)
  • Human Interaction: At least once a week, each rabbit becomes part of human socialization program. The socialization consists of petting, brushing, and/or placing in an exercise pen to get the animals acquainted with human handling. Brushing reduces potential for hairballs.

Hamsters

  • Social Contact: Group housed as much as possible; pair- or group-house hamsters of same gender, except for pregnant females & incompatible animals.
  • Nesting Material: Nestlet, tissue papers
  • Other: Igloo, Jolly Ball™

Xenopus

Being a prey species, Xenopus leavis are provided with shelter objects. The enrichment for X.leavis colony is the provision of PVC pipes. For the group housed X. leavis the number of enrichment (PVC) pipes depends on the density of the animals in the tank.

    • 1 to 5 frogs – 1 PVC pipe
    • 5 to 10 frogs – 2 PVC pipe

Fish

The primary method of environmental enrichment is to be socially housed.  Artificial plants are also provided as environmental enrichment in some tanks to reduce aggression.   If any artificial object is requested for the enrichment of fish requires approval by the Attending Veterinarian.

Spiny Mice

  • Social Housing:  Animals are group housed whenever possible. Female spiny mice may be housed singly due to their aggressive nature.
  • Shelter:  Tubes (polycarbonate or cardboard), Igloos, Nesting materials (shredded paper)
  • Other:  Wooden blocks, Nylon bones, food items (e.g. berries, carrots, apples)

Implementation and Assessment

A successful well-being program depends not only implementing but also on evaluating its effectiveness and constant update to reflect our current knowledge. The principal investigators, research staff, veterinary staff and animal care technicians are involved at all time in decisions regarding psychological well-being and environmental enrichment.

References

  1. Environmental strategies for laboratory animals. ILAR, Vol 46 (2), 2005.
  2. “An Enriched Environment For The African Clawed Frog (Xenopus laevis)”: Lab Animal Magazine, May 1993, Vol. 22, Number 5, pp. 25-29.
  3. Environmental enrichment program for hamsters. Institutional Animal Care and Use Committee, Cornell University, Ithaca, NY.
  4. Guide for the Care and Use of Laboratory Animals – 8th edition. National Research Council, Washington DC. http://grants.nih.gov/grants/olaw/Guide-for-the-care-and-use-of-Laboratory-animals.pdf
  5. Public Health Service Policy on Humane Care and Use of Laboratory Animals, OLAW, NIH. http://grants.nih.gov/grants/olaw/references/PHSpolicylabanimals.pdf

Effective Dates:    May 28, 2026 through June 30, 2029