Welfare of Primates in Laboratories: Opportunities for Refinement

The use of primates in regulated research and testing means that they are intentionally subjected to scientific procedures that have the potential to cause pain, suffering, distress, or lasting harm. These harms, combined with keeping primates in restricted laboratory conditions, are balanced against the potential (primarily human) benefits gained from their use. In this chapter, we provide a brief overview of the use of primates in laboratories, the estimated number, and purpose of use, and summarize the evidence that primates are especially vulnerable and deserve special protection compared to other animals. The 3Rs (replacement, reduction, and refinement) framework, underpinning humane science, is described, and we emphasize both the ethical and scientific needs for refinement. Refinement refers to all approaches used (by humans responsible for their care) to minimize harms and improve welfare for those primates that are still used in research after the application of the replacement and reduction principles. There is a growing body of evidence demonstrating an interplay between animals' welfare and experimental parameters, and that this interplay affects the validity and reliability of scientific output. With this perspective, we argue that it is better to collect no data than to collect poor (e.g., invalid, unreliable) data. It is, after all, unacceptable for primates to suffer in vain and violates utilitarian principles underlying animal use. Furthermore, inconsistency in experimental approach may introduce conflicting results, increasing the likelihood of using more animals, and delaying delivery of promising therapies to the clinic. We focus on mitigating the major welfare issues faced by primates housed in laboratories through coordinated refinements across their life spans. Drawing on examples from cynomolgus macaques (Macaca fascicularis), an Old World monkey commonly used during the development of medical products, we highlight the importance of understanding the critical role humans play in the laboratory, providing environments, performing husbandry, and undertaking procedures that promote welfare and decrease harms. Our theoretical premise is that if primates are to be "fit for purpose" (i.e., well suited for the designated role), we need a proactive, concerted approach for implementing refinement that spans their lifetime.