O mouse, where art thou? The Mouse Position Surveillance System (MoPSS) - an RFID based tracking system

Abstract

Existing methods for analysis of home cage based preference tests are either time consuming, not suitable for group management, expensive and/or based on proprietary equipment that is not freely available. For this reason, we developed an automated system for group housed mice based on radio frequency identification: the Mouse Position Surveillance System (MoPSS). The system uses an Arduino microcontroller with compatible components, it is affordable and easy to rebuild for every laboratory. The MoPSS was validated using female C57BL/6J mice and manual video comparison. It proved to be accurate even for fast moving mice (up to 100 % accuracy after logical reconstruction), and is already implemented in several studies in our laboratory. Here, we provide the complete construction description as well as the validation data and the results of an example experiment. This tracking system will allow group-based preference testing with individually identified mice to be carried out in a convenient manner, creating the foundation for better housing conditions from the animals’ perspective.

Rating enrichment items by group-housed laboratory mice in multiple binary choice tests using an RFID-based tracking system

“…The mouse tag detections were automatically saved onto a microSD card during the experiment and each detection was marked by a current timestamp with the antenna number (left/right) and the individual mouse RFID tag number. Data analysis and sanity checks with logical correction of missing detections were done using a data evaluation script in the software R (R version 4.0.4, R Studio version 1.3.959) specially developed for MoPSS data analysis 29 . Stay times for each of the twelve mice in each cage side were calculated as times between cage changes when a mouse tag was detected at a new cage.…”

“…Stay times for each of the twelve mice in each cage side were calculated as times between cage changes when a mouse tag was detected at a new cage. It has been shown that the time spent in the tube is neglectable for preference calculation 29 and therefore we did not subtract the time spent in the passaging tube. Stay durations over the 46 hours testing period of each single experiment were summed up for each mouse and then calculated as percentage of the total time.…”

“…It is debated whether or not group housed animals can unequivocally considered to act independently in their choice and therefore each cage would have to be considered as one independent sample 25,[31][32][33] . This presents a dilemma because the mice would either have to be housed individually or the total number of experimental animals would have to be increased by the use of additional cages.…”

“…For our preference test, we used the Mouse Position Surveillance System (MoPSS), a new test system constructed in our laboratory 25 . The MoPSS allows automatic long-term calculation of time spent in each of two interconnected cages for each individual mouse in a group.…”

“…For our preference test, we used the Mouse Position Surveillance System (MoPSS), a new test system designed and constructed in our laboratory 31 to ask for enrichment item preferences in female C57BL/6J mice, a widely used strain in biomedical research 32 . The MoPSS allows automatic long-term calculation of time spent in each of two interconnected cages for every individual mouse in a group.…”