Cross-institutional studies that combine non-invasive physiological measures of stress responses and the assessment of individual differences in behaviour and temperament have great potential as tools for assessing the well-being of zoo animals and for identifying key environmental stimuli relevant to well-being. In addition, such studies allow comparison of animals under a wide variety of conditions and enable researchers to obtain sufficiently large samples sizes for statistical data analyses. Faecal corticoid measurements, a method recently developed to monitor adrenal activity in wildlife and domestic species, can be obtained non-invasively as part of the normal husbandry routine. While basic techniques still need improvement, and interpretation of the acquired measures can be challenging, assessment of faecal corticoid concentrations can provide a useful indicator of stress responses under a variety of captive conditions. Here we report on three studies that illustrate this approach and the results that can be obtained. An on-going study reveals significant differences in the pattern of variability of faecal corticoid concentrations between polar bears that are reported by keepers to perform stereotypic behaviour and those that do not. In another study, faecal corticoid measures indicated that stress responses to certain extraneous noises might interfere with the breeding of Hawaiian honeycreepers in captivity. In a study of clouded leopards, higher faecal corticoid concentrations were measured when cats were kept on public display or near potential predators compared to individuals maintained off exhibit or in the absence of visible predators. The findings of an on-going experimental study suggest a causal relationship between the provision of additional hiding spaces and a decline in faecal corticoid concentrations in clouded leopards.

Russell and Burch's Three Rs (replacement, reduction and refinement) remain the cornerstone for principles guiding humane experimental research. However, the concept of refinement has evolved considerably since its first inception and there have been numerous interpretations, some of which are regressive from the original definition. In this paper we examine the interpretations of refinement, and propose a harmonised progressive definition that is in line with changes in animal ethics and animal welfare science. Our definition should be applied to all aspects of refinement: those related to housing, husbandry and care, techniques used in scientific procedures, periprocedural care, health and welfare monitoring, and experimental design. We argue not only that the concept should include the avoidance or minimisation of adverse effects experienced at any time during the life of an animal destined for use in a laboratory, but also that it should be applied to the founder animals. Furthermore, we take a proactive stance and argue that refinement should include enhancing well-being through environmental enrichment. The acceptance and application of this new definition by legislative authorities and in guidelines would represent a significant step forward for animal welfare.