Enrichment-toy trauma in a New Zealand White rabbit

An injury was caused by an enrichment toy (a whiffle ball, which is a perforated hollow ball made of hard plastic) that led to its removal from the rabbit enrichment program. Manipulata and food treats form the basis of the Yale rabbit enrichment program. All singly housed rabbits are given toys such as balls, chains, wood blocks, PVC tubing, Nylabones, and corrugated plastic tunnels. Before they are used, all potential enrichment devices are reviewed for safety and potential veterinary problems. The whiffle ball had been considered safe because it was made of hard non-toxic plastic, had no sharp edges, was too large to be swallowed or inhaled, and was judged too sturdy to be broken by the rabbits. However, the ball became lodged in the incisors of an adult female New Zealand White rabbit, preventing her from eating or drinking for 12 h and causing marked trauma to her gums. Removal of the ball necessitated anesthetizing the rabbit and using bone cutters to cut away the ball. Ideally, environmental enrichment should increase species-specific normal behavior and minimize stereotypies and self- and conspecific-directed abusive behavior. This case illustrates that safety assessments for an enrichment device must include both the inherent properties of the device and the risks if the toy is misused or damaged. Considerations for safety assessment are discussed.