The development of a non-invasive behavioral model of thermal heat stress in laboratory mice (Mus musculus)

- Simultaneous IRT and video capture is a suitable replacement for invasive telemetry devices.
- A plastic arena cover permits IRT and video recording and controls ambient air temperature.
- Continuous IRT and video capture provides very useful data of high resolution and accuracy.

BackgroundMany behavioral and physiological studies of laboratory mice employ invasive methods such as radio telemetry to measure key aspects of behavior and physiology. Radio telemetry requires surgical implants, which may impact mouse health and behavior, and thus reduce the reliability of the data collected.New methodWe developed a method to measure key aspects of thermoregulatory behavior without compromising animal welfare. We examined the thermoregulatory response to heat stress in a custom-built arena that permitted the use of simultaneous and continuous infrared thermography (IRT) and video capture. This allowed us to measure changes in surface body temperature and determine total distance traveled using EthoVision XT animal tracking software.ResultsLocomotor activity and surface body temperature differed between heat-stressed mice and mice kept within their thermal comfort zone. The former had an increase in surface body temperature and a decline in locomotor activity, whereas the latter had a stable surface body temperature and showed greater activity levels.MethodsSurface body temperature and locomotor activity are conventionally quantified by measurements taken at regular intervals, which limit the use and accuracy of the data. We obtained data of high resolution (i.e., recorded continuously) and accuracy that allowed for the examination of key physiological measurements such as energy expenditure and peripheral vasomotor tone.ConclusionsThis novel experimental method for studying thermoregulatory behavior in mice using non-invasive tools has advantages over radio-telemetry and represents an improvement in laboratory animal welfare.