Fluctuating asymmetry of teeth is not a reliable indicator for assessing stress in rats

Abstract

Fluctuating asymmetry (FA) reflects small, random deviations from symmetry in otherwise bilaterally symmetrical characteristics and has been used to detect harmful conditions such as environmental and genomic stress in growing animals and humans. Teeth are often used for measuring FA. especially in humans. The aim of the pressm study was to measure FA in teeth as a possible stress indicator in laboratory rats. Rats housed individually or on a grid floor were compared to rats housed on bedding with or without environmental enrichment. FA of leg traits had been found to increase by housing on a grid floor or individually as compared to housing on bedding and socially. In this study dental FA was found not to be influenced by housing conditions, probably because wear may influence FA of the teeth independent of housing conditions. Incisors in rodents grow continuously throughout life, whereas this growth stops in adult humans. The conclusion of this study is that FA measurements of teeth do not appear suitable as parameters to evaluate stress in rats.