Rowland Sillito1, R Sonia Bains2, Gareth Banks2, Adina T Michael-Titus3, Pat M Nolan2, Will S Redfern4, Jordi L Tremoleda3, Karen Tse4, Sara Wells2, Ping K Yip3 and J Douglas Armstrong1,5
(1: Actual Analytics Ltd, UK.; 2: Mary Lyon Centre, MRC Harwell, UK. S.Wells@har.mrc.ac.uk; 3: Blizard Institute, Queen Mary University of London, UK; 4: AstraZeneca Ltd, UK, 5: University of Edinburgh, UK.
jdarmstrong@actualanaytics.com)
Automated behavioural monitoring in the home cage has obvious and established advantages in improving the consistency of data captured in behavioural experiments, and with 24/7 monitoring also generates a wealth of data that would otherwise be missed [1]. Both of these features have the potential to reduce the number of animals required to achieve statistical significance in experimental study designs and greatly increase the information gathered from animals in research studies. Here we examine an additional technological avenue that can be exploited to further reduce the burden — recording of individual animal behaviour data in group housed mixed cage experimental designs where control and experimental conditions are mixed in the same social group.
While recording animal behaviour in group housed situations already has significant welfare benefits, the ability to analyse the behaviour of identified individual animals within a group housed setting means that the number of subjects constituting each experimental condition does not need to be augmented merely to meet the criterion of having multiple animals in the cage. A range of technologies exist that permit group housed animals to be monitored using combinations of telemetry, gated experimental chambers attached to a home cage and/or video analytics [e.g. 2-4].
Here we will focus on one of these systems, the Actual Analytics Home Cage Analyser [3,4] which allows individual animal behaviour to be recognised within social groups. A range of experiments conducted using the ActualHCA system in both rats [4] and mice [3], show how it is possible to extract insightful behavioural data tagged to individuals. In terms of 3Rs benefits, the obvious advantage over single housed animals in using such a system is Refinement where the stress of isolating the animal from its social group during the study can be effectively removed. This is particularly important in long-term studies, for example in neurodegeneration models [5]. Data in rats also showed that body temperature was lower in isolated animals and that this is prevented by the group situation [4]. There are also additional benefits in that social interactions can be recovered from the data and the potential to observe earlier humane endpoints.
3Rs benefits can also include Reduction in animal numbers by multiplexing the datasets extracted from a single cohort of animals. For example, in a recent pharmacological study [6], we extracted data that partially covered the typical functional observational battery alongside detailed locomotion datasets and temperature all from the same single group of animals. In a typical safety pharmacology scenario each of these studies would normally require an additional cohort of animals. Although the study was designed to validate the system we were able to uncover previously unreported effects of well-known pharmacological standards – largely through the ability to capture detailed data through the night phase.
However the mixed cage approach does raise some new challenges. We will present examples from phenotyping studies (mouse) using single and mixed genotype cages as well as data from surgical and pharmacological studies (both in rat). The data on single animals are already large and extremely complex. To extend into mixed cage analysis the accuracy of identity tracking becomes paramount, despite the limited visual tagging opportunities afforded by freely moving animals in a single home cage. The RFID-driven nature of the ActualHCA system implicitly addresses this problem for locomotor (and, for rats, temperature) data, and provides a vital cue for assigning visually detected behaviours to individuals. A more fundamental challenge is posed by the increasing evidence that mixed conditions can have measurable effects on the control animals in the social group. We will present recent evidence (see Figure 1 for a preliminary example) which demonstrates that mixing various behavioural phenotypes in the cage has measurable influences on the control animals within the social group where the controls acquire aspects of an extrinsic behavioural phenotype.
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In summary, in-cage monitoring of group housed animals does offer very clear 3Rs benefits but, in doing so, adds a new layer of complexity to the underlying experimental design and data analysis.
Animal Husbandry and Ethical Approval
All studies described here were subject to institutional Animal Welfare and Ethical Review Bodies and all procedures were carried out under UK Home Office Project Licenses.
Availability
Data used in this study including video and annotations will be made publicly available under an open license at the time of full publication. Early access may be requested by contacting the authors. The ActualHCA system (hardware variants for both mice and rats, together with corresponding software – currently version 2.4) is marketed by Actual Analytics Ltd (Edinburgh, UK) http://www.actualanalytics.com
Acknowledgements
This work was supported by the National Council for the 3Rs (UK) under the Crack-It Scheme.
References:
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https://doi.org/10.1016/j.applanim.2014.11.018
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3. Bains RS., Cater HL., Sillito RR., Chartsias A., Sneddon D., Concas D., Keskivali-Bond P., Lukins TC., Wells S., Acevedo-Arozena A., Nolan PM. And Armstrong JD (2016) Analysis of Individual Mouse Activity in Group Housed Animals of Different Inbred Strains Using a Novel Automated Home Cage Analysis System. Frontiers in Behavioral Neuroscience 10(106).
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4. Redfern WS., Tse K., Grant C., Keerie A., Simpson DJ., Pedersen JC., Rimmer V., Leslie L., Klein SK., Karp NA., Sillito RR., Chartsias A., Lukins TC., Heward J., Vickers C., Chapman K. and Armstrong JD (2017). Automated recording of home cage activity and temperature of individual rats housed in social groups: The Rodent Big Brother project. PlosONE 12(9): e0181068.
https://doi.org/10.1371/journal.pone.0181068
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Neuroscience Methods 300, 37-47. https://doi.org/10.1016/j.jneumeth.2017.04.014
Figure 1: Preliminary data showing the 24 hour activity patterns of littermate controls housed with two variants of an arrhythmic mutant strain. Pairs of control animals can be seen to deviate from the typical activity pattern of the background strain when group housed with a
homozygous mutant.
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6. Tse K., Sillito RR., Keerie A., Collier R., Grant C, Karpe NA., Vickers C., Chapman K., Armstrong JD., Redfern WS. (2018). Pharmacological validation of individual animal locomotion, temperature and behavioural analysis in group-housed rats using a novel automated home cage analysis system: A comparison with the modified Irwin test Journal of Pharmacological and Toxicological Methods 94(1), 1-13. https://doi.org/10.1016/j.vascn.2018.03.008
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