Environmental Enrichment for Non-Human Primates

Unit for Laboratory Animal Medicine
May 15, 2018 12:00 am

This document outlines the Primate Environmental Enrichment Program (PEEP) developed for the University of Michigan. The program is designed to promote the psychological well-being of non-human primates (NHP) used in research and to provide opportunities for NHPs to engage in non-injurious species-typical activities.

  • Responsibility

    1. Principal Investigator: Determines enrichment strategies consistent with the scientific aims of their research.
    2. PEEP Coordinator: Oversees the overall Primate Environmental Enrichment Program.
    3. Enrichment Coordinator: Recommends and evaluates enrichment items for primate use.
    4. ULAM Husbandry Personnel: Responsible for the daily provision and documentation of enrichment to the animals.
  • Glossary Definitions

    Special Treatment or Procedure (SToP) Form

    A form that indicates special procedure differing from standard operating procedure (SOP). These are typically placed on the inside of the animal room door. See Request for Special Treatment or Procedure (SToP) Form for more information.

  • Procedures

    1. Social Housing

    1. Social species must be housed in social groups or pairs.
    2. Principal Investigators scientifically justify in the Animal Use Protocol if animals cannot be paired or group housed. Some reasons for which animals should not be socially housed include the following:
      1. If use of social housing would invalidate the research project undertaken.
    3. Additional provisions must be made to allow for the social needs of the animal if animals cannot be paired or group housed. These include the following:
      1. The ability to see other animals of the same species. Positioning cages such that animals can see each other or providing mirrors. In all cases, animals should have the ability to hide from the view of other animals.
      2. The ability to smell and hear other animals of the same species.
      3. Physical contact through a partition inserted between the cages for compatible animals.

    2. Animals that Require Special Considerations

    1. SToP Forms can be initiated by investigative personnel, the area supervisor, veterinary personnel or the PEEP coordinator.
    2. Submit completed SToP Forms to the area supervisor for approval.
    3. Veterinary personnel and the PEEP coordinator may exempt participation in the environmental enrichment plan because of the animal's health or physical condition.
      1. The basis for the exemption must be recorded by veterinary personnel for each animal on an Animal Treatment Report (ATR).
        1. Place a yellow acetate on the animal's cage card for animals exempt from the enrichment program.
      2. A veterinarian reviews exemptions to the enrichment program every 30 days unless the condition is permanent.
      3. IACUC approved SToP Forms to the enrichment or social housing program must be reviewed annually by the IACUC.
    4. Consult veterinarians regarding enhancement of an enrichment program for NHPs; which may include:
      1. Infants and young juveniles.
      2. NHPs in psychological distress.
      3. If a NHP exhibits vicious or overly aggressive behavior or is debilitated as a result of age or other conditions (e. g., arthritis).
      4. If a NHP has or is suspected to have a contagious disease and therefore must be isolated from healthy animals.
      5. Those used in research for which the IACUC-approved protocol requires restricted activity.
      6. Individually housed NHPs that are unable to see and hear other NHPs.

    3. Environmental Enrichment Items & Strategies

    1. Principal Investigators must indicate in their IACUC animal use protocol describing which enrichment items and strategies can be provided to primates involved in the research project. The investigator must scientifically justify if providing enrichment would not be compatible with the nature of the research.
    2. Provide an equal level of enrichment to animals housed both in quarantine and in non-quarantine housing areas.
    3. Provide perches within the primary enclosure of all NHPs.
    4. Singly housed primates must be provided additional enrichment above and beyond what is provided to socially housed primates. The code for additional enrichment should be noted on the Non-Human Primate Food and Enrichment Log, and can be provided in any of the means described below or in the NHP approved enrichment database.

    4. Administration of the Enrichment Plan

    1. Personnel provide enrichment records each time enrichment is provided on the Non-Human Primate Food and Enrichment and Log for each animal.
      1. Approved food treats and enrichment items can be obtained from the area supervisor.
    2. Selection and Provision of Appropriate Enrichment Items:
      1. In the IACUC animal use protocol, the Principal Investigator must specify the enrichment devices or approaches that are compatible with the research.
        1. Recharge consumable supplies to the investigator. However, if an investigator requests more enrichment than that selected by the PEEP Coordinator, the investigator may be recharged for the supplementary time and materials.
        2. Specific enrichment items are selected based on animal species and individual size, and provided by the husbandry or veterinary personnel. Selection of items may be made using the Animal Enrichment Database or via consultation with the area faculty veterinarian or PEEP Coordinator.
        3. Ensure smaller enrichment items do not go down the drains and if item can be pushed out through the cage bars, do not use as sole enrichment item.
        4. Remove any enrichment item that is excessively worn or broken and recover all pieces.
        5. If hanging enrichment items are no longer hanging, locate and remove clip/hanging hardware.
        6. Watch for animals ingesting pieces of enrichment items.
        7. Present enrichment devices or activities in the beginning of the workday. Present novel enrichment devices or activities when there is adequate time to observe the animal with them throughout the day.
        8. If an animal has a particular adverse reaction to an item or activity, this item or activity must be recorded on the Non-Human Primate Food and Enrichment Log within the animal room. Report these reactions to the PEEP Coordinator and the faculty veterinarian.
    3. Environmental Enrichment Items and Approaches
      1. Manipulanda
        1. Selection of items to be provided must take into account the size, strength, and behavioral tendencies inherent in the specific species of the non-human primate.
          1. Any items which could pose a strangulation or choking hazard must not be given. Chains must be no longer than 3 chain lengths (see Procedures section 4.d.ii.1).
        2. Frequency of rotating items
          1. Loose items provided within the cage must be replaced minimally every 2 weeks for socially housed NHPs.
            1. Replace or add loose items once per week for single housed NHPs.
            2. Replace or add loose items twice per week for single housed NHPs alone in room.
          2. Items affixed to the outside of the cage must be replaced every 2 weeks provided that there is a safe way to do so.
            1. Care must be taken to ensure that the animal care personnel are not at risk for bites and scratches while removing and replacing the items.
          3. Destructible items such as clean cardboard boxes can be provided. When a given animal is provided a destructible item for the first time, they should be observed to ensure they do not consume the item.
      2. Foraging
        1. Items provided to the NHP that requires them to forage for food/treats. Includes, but not limited to, puzzle feeders, frozen blocks, destructible.
          1. Socially housed NHPs must be offered at least once per week.
          2. Single housed NHPs in room with conspecifics must be offered at least three times a week.
          3. Single housed NHPs alone in a room must be offered every weekday.
      3. Food-based treats
        1. Husbandry personnel must receive approval by investigative personnel prior to introduction of novel food items. Investigative personnel may wish to restrict the amount or types of food if it will interfere with the study.
        2. The appropriate amount of each food-based treat for each species will be determined by the PEEP coordinator, area faculty veterinarian, or area husbandry supervisor.
          1. The quantity of food provided should not be such that it results in the animal becoming overweight.
          2. Husbandry personnel should consult with the area supervisor regarding the appropriate amount of food to be provided in the form of enrichment.
        3. Provide approved food treats at a minimum of once a day excluding weekend and holidays (unless the lab requests additional treats otherwise).
          1. Fruit regularly provided to an animal can be considered a food treat.
        4. Provide animal's normal diet as well as treats in a foraging device or puzzle, whenever possible.
      4. Interaction (without direct contact) with husbandry personnel or other familiar persons should be encouraged.
      5. Room level enrichment.
        1. Provide TV to all NHPs daily.
        2. Singly housed NHPs alone in a room must also be provided the radio or sound machine daily and have a mirror at all times in addition to daily TV.
        3. Bubble machine and popcorn machine are other forms of room level enrichment that can be provided.
      6. See Appendix B for hanging room poster quick guide for minimum environmental enrichment strategies.
    4. Enrichment Items Not to be Provided
      1. Those items indicated by the lab or that are not consistent with caging requirements.
        1. For example, items should not be placed in the cage if they will impede the ability to immobilize the animal (e.g. large items placed in squeeze-back cages).
      2. Any items which could pose a strangulation hazard should not be given.
        1. For example, no circular devices should be provided which are large enough to be placed over the animal's head. No chains, cables, or ropes should be provided which are long enough to encircle the animal's neck.
      3. No items containing batteries should be provided within reach of any non-human primate.
      4. Any item that could pose a choking hazard or whose ingestion could harm the animal.

    5. Animal Concerns

    1. Any concerns regarding the Primate Environmental Enrichment Program can be addressed to any of the following individuals or groups involved in the care of the animals:
      1. ULAM husbandry supervisor or manager
      2. Veterinary personnel
      3. The PEEP Coordinator
      4. The ACU Office
      5. The IACUC-sponsored anonymous Animal Concern Hotline (734-763-8028)
  • Appendix A: Nonhuman Primate Enrichment and Husbandry Log

  • Appendix B: Nonhuman Primate Minimum Enrichment Room Poster

Species: Primates
Topic: Enrichment

Questions or concerns about the content of this document should be directed to the Unit for Laboratory Animal Medicine (ULAM) at (734) 764-0277 or