I had and have Brit pups that did/do the same thing. Earlier I put a cheap little area rug in the crate that had a woven plastic backing. Mistake. Pup had an ordeal passing a three inch long strand of stiff plastic - plus a $$ vet visit. Follow Jonny B's recommendation about rubber backing - tough, dense rubber. I also have a soft pad for the vehicle crate that the pup has not been able to chew up or tear open. Unfortunately, not sure now where I got it, but Walmart probably.