Rats are always going to chew. It is instinct. Their teeth never stop growing and they must chew on wood and other things to keep their teeth ground down. You will need a cage suitable for rats that...
Bitter Apple, spray it on what the dog chews most and the taste will make him stop chewing that item eventually after tasting it on enough items or depending on how bad the habit is he will stop...
Bitter apple spray worked well for us, but it was one or two specific areas of the carpet. It may not be a feasible solution if it is a very large area that's being chewed on. Should be able to find...