Hello Ainslie,
My Moo-Moo scratches his mouth on his bed.
I bathe with Hibiscrub every couple of days in the lip fold area to keep it clean.
Incidentally, he has had his anal glands removed as well.....wonder if it is connected?
Just before Christmas he had been 'scooting' along the floor if I wasn't looking and had made under his tail sore. We went to the vets as he had been 'nibbling' his skin further down from his bum-bum as well.
The vet thinks it may be an allergy, to what I don't know until he does the tests. I cannot change his diet as he is prone to struvite crystals so it is a process of elimination. I have started to use a dermatological washing powder (Surcare) for his and the other dogs bedding and touch wood, he hasn't done it much since then.
Hope this helps,
Heather