Abstract: Evaluating automatic detection of incompatibility between male mice for timely intervention using TrackPaw

A collaboration between TrackPaw and AstraZeneca.

Abstract

1 : Animal Science and Technology, Clinical Pharmacology and Safety Sciences, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden

2: TrackPaw Scientific AB, Lund, Sweden

Group housed male mice can develop aggressive behaviour as social hierarchies form. When dominance and submission do not stabilise, fighting may escalate, compromising both animal welfare and data quality. Currently, incompatibility is identified through daytime manual checks, which may detect issues only after overt signs, such as visible fighting wounds have appeared. Because this method does not provide continuous monitoring during the mice’s peak activity periods, aggressive altercations can be missed between inspections, increasing the risk of preventable harm.

To find means for more predictive and targeted interventions, TrackPaw Scientific AB, in collaboration with AstraZeneca, is developing an automated home cage monitoring platform for group housed male mice. TrackPaw is a weight sensor and RFID based system that replaces the standard cage in the rack and continuously tracks weight and movement of microchipped mice. Using these data, the system detects high intensity events (HIE) indicative of ongoing aggressive behaviour and alerts users when predefined thresholds are exceeded.

To assess how HIE alerts can be used for practical colony management, 30 C57/Bl6 male mice (4 weeks old) were monitored in groups of three over 56 days using TrackPaw. Building on a previous study of 21 C57 male mice, where camera surveillance served as ground truth and false alarms were rare, this study aimed to define an alert threshold that would enable separation prior to incompatibility activities reaching their peak and before visible damage occurs. An optimal threshold of HIE was set at 180 seconds of detected activity within each 24-hour window (6 PM to 6 PM), and TrackPaw alerts enabled timely, targeted interventions in the relevant cages.

The next step is to identify how climbing ties into the story, how RFID could be used to identify potential aggressors, and to compare similar baseline measurements for females of the same age, to streamline the process of separation and improve animal welfare.