Document type: Scientific article published in Frontiers in Animal Science
Authors: Schuck-Palm C, Alonso WJ, Hartcher K, Chiang C, Pereira PA, Veit W, Mendl M, Nicol CJ, and Lecorps B
Preview: Pain is not solely a function of tissue damage but can be strongly shaped by environmental context. Its perceived intensity, duration, and likelihood—the core features of affective experience—are modulated by factors including opportunities for behavioral engagement, control over environmental conditions, social environment, physical activity, sleep quality, maternal stress and pain early in life. All of these factors affect pain responses of captive animals, yet most welfare assessments and mitigation protocols treat pain as if it were context-invariant. Here, we review multiple lines of evidence indicating that environmental and rearing conditions modulate pain processing and healing in captive animals. We show that barren, confined environments disable multiple endogenous analgesic mechanisms, while simultaneously activating several neurobiological pathways that intensify nociceptive signaling and delay healing. Pain perception amplification and impaired healing are particularly likely when captivity is associated with intensive and barren environments. The implications of these findings are substantial. First, they highlight the need for animal welfare assessment models, and animal welfare research in general, to take environmental modulation of pain explicitly into account. Likewise, certification and regulatory frameworks must acknowledge that seemingly identical ailments or procedures can produce fundamentally different welfare experiences depending on the environment where they take place. Additionally, analgesic dosing protocols and laboratory-based pain models must be reevaluated for translational validity. More broadly, these findings challenge the acceptability of barren housing systems ubiquitous in farms, laboratories, and other settings. Given the substantial evidence that barren environments amplify and prolong painful states from common routine procedures and ailments, the transition to higher welfare housing systems becomes an ethical and scientific imperative.
