I thought I would post this message from the RWAF Veterinary Specialist Advisor, Richard Saunders re giving Rabbits cardboard toys to play with. The message was posted on the RWAF FB page :
''We are aware of lots of comments regarding cardboard at the moment,
Cardboard toilet and paper towel roll inners can be very useful as an enrichment tool, and many many rabbit owners use boxes filled with hay and with holes cut inside, or toilet roll inners stuffed with hay etc without problem, and have done for years, because we didn't have the vast array of toys to chose from that we have now. Cardboard boxes filled with bedding are useful for extra insulation in the winter. Cardboard boxes with 2 holes cut in them are useful as a bolt hole for the rabbits to feel safe.
Obviously as rabbit owners, if you see your rabbits eating a lot of the cardboard, rather than just enjoying destroying it, then remove any cardboard items, and consider seeking veterinary advice.
As a Specialist Vet, I see rabbits eating both appropriate and inappropriate fibrous and indigestible materials when they have GI problems, and this may be a sign of such issues. As with "hairballs" it's often that the fur, hair, cardboard etc is in the gut in large amounts BECAUSE the GI tract is moving slowly, not causing the problem. What I am saying here is that when the rabbit starts to become ill, they often eat things that are not appropriate, and the cardboard or hairball is in the gut because of the gut slowdown, and is not the cause of it. Of course, there are certainly rabbits out there (as with dogs etc), who definitely eat things to excess, inappropriately, and in such cases, in any species, it's sensible to prevent a problem by not allowing access to the material in question.
So let your rabbits enjoy their cardboard toys, but as with any toy, be sensible and monitor them. There are lots of things that you can give your rabbits to actually chew and eat that are safe such as apple branches, willow branches, hazel branches and forage trays.
Richard Saunders
BSc (Hons) BVSc FRSB CBiol DZooMed (Mammalian) DipECZM(ZHM) MRCVS; RCVS Specialist in Zoo and Wildlife Medicine (Mammalian); European Specialist in Zoological Medicine (ZHM); RWAF Veterinary Specialist Adviser''