Single Housing of Primates in US Laboratories: A Growing Problem with Shrinking Transparency.

In 1985, in response to high-profile cases documenting the mistreatment of non-human primates used in experiments,1 the US Congress amended the federal Animal Welfare Act (AWA) to mandate that institutions take steps to promote the psychological wellbeing of primates in laboratories.2 As a result, the US Department of Agriculture (USDA) created regulations pertaining to environment enhancement for primates, including provisions aimed at addressing their social needs.3 In federal regulations and guidelines, social housing of primates is now deemed to be the ‘default’, with exemptions permitted only for veterinary or experimental reasons with appropriate documentation and approval.4 In cases in which an experiment-related exemption was granted, institutions have been required to submit these written and approved justifications to the USDA with their annual reports on animal use. These documents — which report the number of primates singly housed for experimental reasons, and why it was deemed necessary — were then made publicly available.