Environmental Enrichment – Swine


Boston University is committed to observing Federal policies and regulations and AAALAC International standards for the humane care and use of animals.1 This policy provides guidelines for providing environmental enrichment (EE) for pigs.

 Humane considerations and current policies require that research animals, whenever possible, must have the opportunity to interact with conspecifics and to benefit from EE.   Pigs are social animals that become stressed when isolated; thus housing pigs in the same room where they can see, hear, and smell each other is a form of EE.  Pigs are also intelligent animals with good memories; if handled gently from a young age they interact well with humans.  It is consistent with the goal of implementing and maximizing one of the three Rs, i.e. Refinement, to provide pigs with EE.

I.    PURPOSE           

A.   To define environmental enrichment for pigs, including various ways to “facilitate the expression of species-typical behavior and promoting psychological well-being through physical exercise, manipulative activities or cognitive challenges”.1

B.   To outline how exceptions to this policy should be considered by the IACUC or BU ASC veterinarians. 


  1. While pigs will not be group-housed in the same pens, at least two pigs will be housed in the same room where they can clearly see, hear, and smell each other. Supervised exercise of individual animals outside their runs may also be implemented as a form of enrichment. If sex and temperament permit, pigs will be housed in adjoining pens such that they can make nose-to-nose contact, as well. For personnel and animal safety, however, adult males and females of breeding age may require pens that do not adjoin each other. In these instances, the pigs will still have auditory, visual, and olfactory access to each other. 
  2. If a protocol exception to limit or exclude enrichment is to be included in an IACUC submission, the PI is required to consult with veterinary staff during protocol development to discuss the special circumstances that might limit participation in the enrichment program.  The Principal Investigator (PI) will need to include the requirement and scientific justification for the requested exemptions from any EE strategies included in this policy or associated SOP.  If no exemptions are approved within the protocol, then the policy and associated SOP will be followed.  Once the protocol is approved, the PI must inform BU ASC of the approved exceptions to this policy.
  3. Pigs may be provided with extra cage enhancements unless an exception to limit or exclude EE is justified in an IACUC-approved protocol for scientific reasons.  Pigs will be observed daily and will have their well-being evaluated at least monthly by a veterinarian or other adequately trained BU ASC staff.  The assessment and recommendations for continued limitations to EE will be reviewed and approved by the Attending Veterinarian or designee. 
  4. In circumstances where there is only one pig per room (e.g. quarantine), BU ASC will provide extra enrichment in collaboration with the PI.

III.  Enrichment devices

  1. Several vendors provide an assortment of enrichment devices and treats.  These may include Nyla bones or other chew toys, balls, food treats, and feeding troughs or other devices which fit in the cages without crowding the animals and can be either discarded at cage change or sanitized.
  2. BU ASC staff will be responsible for the administration of the enrichment program including replacement of devices that are heavily soiled, malfunctioning, or in poor working condition.
  3. If a PI has received approval in a protocol that the pigs on study will receive edible treats for enrichment, these are best given by the PI or research staff as part of the study.  The administration of these edible treats should be clearly documented in the animal’s records.



1.   The Guide for the Care and Use of Laboratory Animals. 2011.  NRC ILAR.  P. 52-55.  Environmental Enrichment.

BU IACUC Approved: September 2012