A systematic review of the development and application of home cage monitoring in laboratory mice and rats

Abstract

Background Traditionally, in biomedical animal research, laboratory rodents are individually examined in test apparatuses outside of their home cages at selected time points. However, the outcome of such tests can be influenced by various factors and valuable information may be missed when the animals are only monitored for short periods. These issues can be overcome by longitudinally monitoring mice and rats in their home cages. To shed light on the development of home cage monitoring (HCM) and the current state-of-the-art, a systematic review was carried out on 521 publications retrieved through PubMed and Web of Science. Results Both the absolute (~ × 26) and relative (~ × 7) number of HCM-related publications increased from 1974 to 2020. There was a clear bias towards males and individually housed animals, but during the past decade (2011–2020), an increasing number of studies used both sexes and group housing. In most studies, animals were kept for short (up to 4 weeks) time periods in the HCM systems; intermediate time periods (4–12 weeks) increased in frequency in the years between 2011 and 2020. Before the 2000s, HCM techniques were predominantly applied for less than 12 h, while 24-h measurements have been more frequent since the 2000s. The systematic review demonstrated that manual monitoring is decreasing in relation to automatic techniques but still relevant. Until (and including) the 1990s, most techniques were applied manually but have been progressively replaced by automation since the 2000s. Independent of the year of publication, the main behavioral parameters measured were locomotor activity, feeding, and social behaviors; the main physiological parameters were heart rate and electrocardiography. External appearance-related parameters were rarely examined in the home cages. Due to technological progress and application of artificial intelligence, more refined and detailed behavioral parameters have been investigated in the home cage more recently. Conclusions Over the period covered in this study, techniques for HCM of mice and rats have improved considerably. This development is ongoing and further progress as well as validation of HCM systems will extend the applications to allow for continuous, longitudinal, non-invasive monitoring of an increasing range of parameters in group-housed small rodents in their home cages.

Environmental enrichment: a systematic review on the effect of a changing spatial complexity on hippocampal neurogenesis and plasticity in rodents, with considerations for translation to urban and built environments for humans

“…Furthermore, new paradigms could be employed in rodents to explore the effects of spatial complexity, namely: (a) smart cages, i.e., complex cages containing technological interactive elements that allow automated home-cage behavioral monitoring ( Mingrone et al, 2020 ; Voikar and Gaburro, 2020 ; d'Isa and Gerlai, 2023 ; Kahnau et al, 2023 ; Lipp et al, 2024 ); (b) seminatural environments, i e. housing environments that reproduce in the laboratory elements of the natural habitat of the hosted species ( Hernández-Arteaga and Ågmo, 2023 ); (c) freely accessible complex mazes connected directly to the home-cage, such as the automated eight-arm radial maze designed by the Julius Emmrich laboratory ( Mei et al, 2020 ; Kohler et al, 2022 ); (d) radio-collars allowing radio-tracking of free-ranging rodents living in their natural habitat ( Stradiotto et al, 2009 ; Bonacchi et al, 2021 ).…”

Editorial: Animal-friendly methods for rodent behavioral testing in neuroscience research

“…The best example of open-session animal-friendly behavioral testing are the automated home-cage monitoring systems (Mingrone et al, 2020 ; Voikar and Gaburro, 2020 ; Grieco et al, 2021 ; Kahnau et al, 2023 ), which avoid potentially stressful animal handling, do not require removal of the animals from their home-cage for testing in unfamiliar and hence potentially anxiogenic environments, permit the animals to be tested in a social context together with their mates and respect the circadian rhythms of the tested subjects. The most widely known of these systems is IntelliCage, conceived by Hans-Peter Lipp and collaborators in the early 2000s at the University of Zurich (Galsworthy et al, 2005 ; Lipp, 2005 ; Lipp et al, 2005 ).…”

Appetitively motivated tasks in the IntelliCage reveal a higher motivational cost of spatial learning in male than female mice

“…These shortcomings have, therefore, created an urgent need to develop new, more efficient approaches to behavioral phenotyping of mice. Therefore, a number of computer-assisted technologies for automatically capturing rodent behavior in the home cage over long periods of time have been developed ( Gerlai, 2002 ; Spruijt and Devisser, 2006 ; Goulding et al, 2008 ; Endo et al, 2011 ; Kahnau et al, 2023 ). Among them, the IntelliCage (IC) is a unique approach because the system is specifically designed for the cognitive assessment of group-housed mice.…”