The BMC endorses social housing as the foundation of welfare for research nonhuman primates who are members of species that live socially in the wild. Scientific literature establishes that socially-housed primates demonstrate well-being that is superior to that of their singly-housed counterparts, and that introduction of singly-housed primates into a compatible social setting improves their welfare by a variety of behavioral and physiological measures. For example, social housing reduces the expression of species-inappropriate behaviors, promotes species-appropriate activities and can buffer individuals from stress.

Endorsing the importance of social housing is consistent with the positions of the United State Department of Agriculture (USDA), the Office of Laboratory Animal Welfare (OLAW), and AAALAC, International. Social housing also meets the standards outlined in The Guide for the Care and Use of Laboratory Animals, specifically the statement that, “Social animals should be housed in stable pairs or groups of compatible individuals unless they must be housed alone for experimental reasons or because of social incompatibility” (National Research Council, 2011, p. 64). The BMC endorses the concept that the form of housing that involves the least restriction to social experience should be employed whenever practical. Even social housing for some portions of time or providing a limited degree of social contact should generally be seen as superior to individual housing.

The Animal Welfare Act requires social housing, but with several conditions deemed as appropriate justifications for exceptions from social housing. Single housing is permissible when an animal is deemed vicious or overly aggressive such that compatible partners cannot be identified, is debilitated, has or is suspected of having a contagious disease, or is exempted because of health condition or scientific requirements approved by the local Institutional Animal Care and Use Committee (IACUC; USDA 2017, p. 175-176). There are also many other factors that may influence a research primate’s housing situation. Maximizing an animal’s lifetime social housing is aided by constant awareness of the reason for single housing and swift attention to any issues that can be addressed to end single housing. The BMC recommends that facilities document and regularly review not only exemptions from social housing (as is required in the Animal Welfare Act) but also reasons not covered in the regulation. We have developed a categorization system outlining 14 different factors relating to the use of single housing (see table below).

By using this system for tracking the reasons research primates are singly housed, facilities can quantify the circumstances associated with the use of single housing, and work to remedy those obstacles to social housing that can be altered. For example, tracking the number of animals that are singly housed at any particular point in time because appropriate caging is not available, can justify the need for additional caging purchases. If an increasing number of potential partners cannot be introduced because they have yet to be moved into place, suggests the need for coordination and planning with animal care personnel responsible for animal moves. The BMC recommends the use of this categorization process to strengthen social housing programs and to allow objective evaluation by other groups (e.g., IACUCs, USDA, AAALAC International).

This table is available in Baker et al, 2017.

---

BMC Categorization of factors leading to the use of single housing (modified from Baker et al., 2017)

Animal Welfare Act Exceptions

Scientific: Scientifically justified exception approved by the Institutional Animal Care and Use Committee

Veterinary: Approved veterinary exception. May include quarantine

Behavioral: Animal has intrinsic behavioral characteristics that may preclude social housing (e.g., hyper aggressivity)

Reasons for single housing: practical issues not addressed in the AWA

No potential partner: Odd numbers of animals in a study or within the treatments groups that cannot be intermingled; only potential partners are the opposite sex, and neither breeding nor birth control are permitted

No potential partner (viral): Nonexperimental viral status (e.g., specific pathogen free status)

No compatible partner: was not successfully paired after multiple introduction attempts with partners of various demographics (e.g., age, sex, rearing conditions, etc).

Space: No space in the room where the animal must remain due to project assignment, status, or room dimensions

Caging: No caging permitting social housing is available

Investigator information required: Information needed from Principal Investigator, such as treatment group assignment, current phase of project, and approval of proposed pairs

Experimental results required: Waiting for experimental results (e.g., experimental viral status)

In process: Partners are in the process of the social introduction but are still single housed (e.g., may be in protected contact)

Nonexperimental viral results required: Animals cannot be paired until results concerning naturally occurring pathogens are received

Clinical procedures required: Waiting for clinical procedures that will allow pairing (e,g., vasectomy)

Moves: Waiting for appropriate caging to be moved in place and animals to be relocated so that introductions can occur

Behavioral management queue: Animals are in the queue for future social introduction, and behavioral management staff is preparing to make queries that require responses or actions of individuals outside the unit (e.g., reading scientific protocol, preparing questions for Principal Investigator, determining potential partners, preparing move requests), or the introduction is scheduled but has not yet commenced

Timing: Potential partners will not be able to remain together for a long enough period of time for a net gain of animal well-being to be likely, given transient introduction stress and possible separation stress; animals will be sold in a short period of time; potential pair will imminently be assigned to research projects that do not permit social housing

Removal or death of partner: Partner removed for clinical reasons or mortality; remaining animal not yet scheduled for reintroduction or placed in behavioral management queue

---

References Cited:

Baker, K, Bloomsmith, M, Coleman, K, Crockett, C, Lutz, C., McCowan, B., Pierre, P., Weed, J., and Worlein, J. (2017). The Behavioral Management Consortium: A Partnership in Promoting Consensus and Best Practices. Pp 9 – 23 in the Handbook of Primate Behavioral Management. CRC Press, New York, Steve Schapiro (Ed).

National Research Council (Institute for Laboratory Animal Research). 2011. The Guide for the Care and Use of Laboratory Animals. Washington, DC: National Academy Press.

U.S. Department of Agriculture. Animal Welfare Act and Animal Welfare Regulations. 2017. Section 3.81 – Environmental enhancement to promote psychological well-being. Animal Welfare Act and Animal Welfare Regulations (“Blue Book”).

---

For more information regarding NPRC Behavioral Management resources, please contact support@nhprc.org.