Running wheel choice by Syrian hamsters.

The present study investigated the preference of male and female Syrian hamsters, Mesocricetus auratus, for different types of running wheels. Hamsters were placed individually in sets of multiple cages linked by tunnels, each cage with a different running wheel. The number of wheel revolutions in each cage was tallied daily over 40 days. The hamsters did not express a preference when offered a choice of a running surface made of metal rods spaced 9 mm apart and a similar running surface covered in plastic mesh to prevent the possible slippage of feet between the rods. The hamsters did express a clear preference for larger wheels (35 versus 23 cm diameter), and for completely circular wheels over truncated ones. They neither favoured nor rejected wheels with small obstacles along the running surface. In all experiments, preferences were more strongly expressed by males than by females. Running wheels for hamsters may be improved by enlarging their diameter (to the standards often used for rats, if practically possible) and by ensuring good footing on the running surface (a space no larger than 9 mm between evenly spaced rods seems sufficient to achieve this, at least in large wheels and for hamsters older than 55 days). Installing obstacles along the running surface does not appear to make the wheel more interesting to hamsters.