Abstract
Simple SummaryGrimace scales for laboratory animals were first reported ten years ago. Yet, despite their promise as pain assessment tools it appears that they have not been implemented widely in animal research establishments for clinical pain assessment. We discuss potential reasons for this based on the knowledge gained to date on their use and suggest avenues for further research, which might improve uptake of their use in laboratory animal medicine.Animals’ facial expressions are widely used as a readout for emotion. Scientific interest in the facial expressions of laboratory animals has centered primarily on negative experiences, such as pain, experienced as a result of scientific research procedures. Recent attempts to standardize evaluation of facial expressions associated with pain in laboratory animals has culminated in the development of “grimace scales”. The prevention or relief of pain in laboratory animals is a fundamental requirement for in vivo research to satisfy community expectations. However, to date it appears that the grimace scales have not seen widespread implementation as clinical pain assessment techniques in biomedical research. In this review, we discuss some of the barriers to implementation of the scales in clinical laboratory animal medicine, progress made in automation of collection, and suggest avenues for future research.
Highlights
Animal welfare is an important societal concern [1,2]
Corticosterone measures in this study suggest that the pain response was short-lived and had resolved by 1-h post-procedure
If grimace scales are to be implemented as a routine clinical assessment tool in biomedical research facilities, there needs to be a clear understanding of whether they are specific to pain, and can reliably measure pain in the models being used
Summary
Animal welfare is an important societal concern [1,2]. The use of animals in biomedical scientific research is widespread, and globally significant, with approximately 115 million animals used per year [3]. Evaluation of complex motor responses, such as facial and corporal expression was proposed as a neurobiological readout of mammalian brain neuro-circuitry associated with emotional experience [11,15,16,17] The former has received significant research attention, especially in rodents, as a potential assessment method for both positive and negative emotional states [9]. The utility of the scales was well-established across a range of laboratory animal species and animal model types This evaluation has typically focused on their use via retrospective video recording review, and as a research tool to obtain data relevant to the animal model. It is anticipated that this review will guide biomedical researchers, animal technicians and ethics committees when implementing pain assessment methods as part of research protocols
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