Duncan, A. E. 1997. A veterinary assessment of the risks and benefits of environmental enrichment.

Toys or parts of toys might be swallowed and cause choking or asphyxiation.Enrichment foods fed in excess may cause bloating or diarrhea.Frayed cargo nets and ropes and deteriorated support structures may cause physical injury.Favored foods or items may cause competition and aggression.Clothing, towels, burlap bags, ropes and hair might cause linear foreign body impaction.Rawhides, pig ears, bones and other items may cause gastrointestinal impaction.Bones or other hard objects may cause teeth to chip or fracture.Excessive enrichment stimuli may cause stress.Ropes and chains can cause trauma or choking.Natural substrates can harbor parasites, bacteria, viruses, and fungal organisms.Burlap, fabric, and natural fiber threads can cause constriction injuries to fingers and toes.Metal hardware used to construct enrichment items may cause heavy metal intoxication or foreign bodytrauma.Introduced items act as fomites- rotating items between animals can transmit disease.Fecal material, body fluids, antlers, elephant foot trimmings, etc. have potential to transmit disease if usedfor enrichment.Insects fed in large numbers can cause impaction or stool changes due to high chitin content.Buttons, string, tape, staples, inks, and some dyes must be removed from items offered.Volunteers may not always build enrichment items to your specifications.Browse toxicity is not known in all species.Food items not eaten must be removed before spoiling occurs.Enrichment foods might cause animals to consume a lower proportion of their formulated diet.Excessive feeding enrichment can cause obesity.