I have started having issues with my 7 month old Aussie puppy chewing off her collar when she is in her crate. I have always used Combo callars on my dogs and have never had this issue. The collars are fitted correctly but when I realized what she was doing I tightened the collar a little hoping that would help. It didn't though.
We were out of town this week and I realized she was starting on her collar so I made the decision that while she was in the crate she was not going to wear one. Well, my daughter put her in the crate and forgot. We were gone maybe 45 minutes after spending most of the day at the lake (dogs were there swimming and running around) and the collar was destroyed. So I ended up having to buy a choke chain because we were in an area where there are no pet stores and I was lucky to find that.
I am kind of thinking about letting her wear the choker for a while and maybe that would teach her not to chew on the collars but I don't like the Idea of leaving that on her in the crate either. I really hope this is just a phase and it will pass. She gets plenty of excersise so I can't imagine that she would be bored but who knows.
But I would love to hear some other ideas.