Multidisciplinary assessment of cumulative experience of laboratory macaques

Format of work:

Conference Presentation

Event presented at / Journal Name:

Seventh Annual Meeting of AWRN

Speaker / Contact Author's Name:

Janire Castellano Bueno, Newcastle University

Speaker / Contact Author's E-mail Address:

  • Research aim:

    Assess the cumulative experience of laboratory rhesus macaques involved in neuroscience experiments and to identify factors that could be impacting it.

  • Background:

    Rhesus macaques (Macaca mulatta) are widely used in biomedical research due to their phylogenetic proximity to humans and their ability to perform complex cognitive tasks. Optimising their welfare is essential from both an ethical and a scientific perspective. Welfare concern due to their extensive stays at research facilities is increasing and led to the introduction of the concept of cumulative experience (defined as the net impact of all events that affect adversely, positively and by way of amelioration, the welfare of the animal over its lifetime). The importance of assessing cumulative experience in laboratory macaques has been highlighted in research regulation.

  • Approach:

    We used new validated behavioural and neuroimaging indicators of cumulative experience, as well as currently used indicators of welfare based on alopecia. We refined the use of the behaviour Inactive not alert to maximise its sensitivity and specificity as a marker of cumulative experience by testing different durations as well as estimating the number of sessions required to assess reliably the frequency of the behaviour.

  • Key finding:

    We found evidence of negative cumulative experience in laboratory macaques involved in long-lasting neuroscience experiments (evidenced by two independent welfare indicators: increase in alopecia and the frequency of Inactive not alert behaviour over time). Modelling work suggest that this latter effect is caused by the daily involvement in experiments (including transient separation from the cagemate, head fixation, proximity with humans). The effect is small, compared to other factors known to have a detrimental impact on the welfare of macaques (e.g. chronic single housing). The effect of other procedures and events, such as anaesthesia, dura scrapes and fights/infections were found not to have cumulative effects over years.

  • Industry or policy relevance:

    The prospective severity of neuroscience experiments has recently been changed from ‘moderate’ to ‘severe’. This choice was motivated by the expectation that the effects of all experimental procedures will be cumulative. This hypothesis is not supported by our results. The prospective severity banding of these experiments should be reconsidered. Some procedures can have a cumulative negative effect on laboratory macaques over years. Such cumulative effects must be taken into account when assessing the retrospective severity of protocols and human end-points. The negative effect of transient separation from the cagemate might have been under-estimated: this should be the topic of further investigation. To minimise animal suffering, valid and sensitive welfare indicators must be used.

  • Route for practical application:

    The revised version of alopecia scoring we have used is easy to implement in industry and seems to be sensitive to detect small variation in welfare over years in large groups of macaques. To detect small variation of welfare over a shorter time scale (within weeks/months) and in single (or small group of) individuals, the monitoring of the behaviour ‘Inactive-not-Alert’ seems to be efficient when done via remotely-controlled cameras. Quantifying this behaviour is time and labour intensive. It would need to be automatized (with deep learning algorithms for instance) to be used at a wider scale in industry.

  • Confidence in findings and next steps towards realising impact:

    Choice of welfare indicators was based on their validity. Welfare indicators were refined to maximise their sensitivity and specificity. Evidence come from two independent welfare indicators. Confidence in findings (positive results for daily involvement in experiments and negative findings for other procedures) is thus high. The findings are only relevant for the frequency of the procedures observed during the study. These frequencies are representative of what is common in cognitive neuroscience experiments in macaques in the UK. However, results might be different in case of significantly different frequencies: for instance, if the involvement in experiments is more sparse, its effect might not accumulate; similarly if fights/anaesthesia/ dura scrapes were much more frequent, their effect might accumulate).


NC3Rs, Barbour Foundation, UFAW

Links to Open Access Publications or DOI:


Castellano-Bueno, J. 2023. “Multidisciplinary assessment of cumulative experience in laboratory rhesus macaquesSeventh Annual Meeting of AWRN, Great North Museum, Newcastle. 18-19th January 2023.