Lopez Juaristi, 2019. A comparison of enrichment items for the promotion of natural gnawing behaviour in laboratory mice. Animal Technology and Welfare 18(2), 93-97.

Appropriate housing and husbandry, including environmental enrichment, must take the natural habitat, biology and behaviour of each species into consideration. The Guide for the Care and Use of Laboratory Animals (1996) states that the goal should always be to maximise species-specific behaviours and minimise stress-induced behaviours. The aim of the study was to compare different chew items available for laboratory mice (Aspen chew stick, flat chew stick, Aspen brick, lolly stick, Aspen ball) to decide which one is the most suitable as part of cage enrichment for fulfilling animals’ natural needs such as gnawing (promoting teeth wearing). According to the results we should rotate chew items during weekly cleaning process to keep animals’ interest on gnawing to prevent habituation to enrichment and any health impact. The difference in shape and materials are decisive factors. The flat chew stick and aspen brick are different in both shape and wood. The first one is bigger and flat birchwood, while the brick is thicker, smaller and made of Aspen wood. Considering the cost and disturbance factor the recommended strategy for best animal welfare will be: 1. Rotate the chew blocks between the flat chew stick and the aspen brick. 2. Change the enrichment when cleaning cage to avoid unnecessary disturbance, unless the item is completely gnawed before cleaning.