The influence of different types of behavior on the eye temperature of mice using infrared thermography

Abstract

Stress is an important factor that affects the welfare of mice used as research animals and therewith the reliability of research results. Currently the most common way of measuring stress levels is testing corticosterone levels from blood samples. However, taking these blood samples is invasive by itself and therefore a less invasive method thatis reliable is an improvement.

Using infrared thermography to measure stress-induced hyperthermia could be such a non-invasive method. To use this method properly the different influences on the surface temperature of the body have to be explored. Previous research indicates that other factors may influence the surface temperature of animals. In this research the influence of different types of behavior on the eye and tail temperature of male C3H mice was explored.

16 male C3H mice were put in a testing cage for 30 minutes, for 5 consecutive days. The behaviors of the individual mice were logged continuously and the eye and tail temperature were measured using infrared thermography and were analyzed for every 5 minute interval. The different behaviors were divided into active and inactive behaviors, the duration of behavior of both groups were compared. Spearman’s correlation test was run to explore the correlation between the duration of each separate behavior and the two behavior groups and the tail and eye temperature of the mice.

The results show a positive correlation between active behaviors and the eye temperature, and a negative correlation inactive behaviors and the eye temperature. The tail temperature the opposite was found; a positive correlation with the duration of inactive behaviors and a negative correlation with active behaviors.

This shows that behavior and activity level is something to consider during research toward body temperature and eye and tail temperature. However, stress-induced hyperthermia was still measurable in the same data. This means that this method, if explored more thoroughly in the future, might be used to indicate stress in laboratory animals.