My cat is 6 years old and we have had the same cat-carrier since he was a kitten. He doesn't like it much and I find it awkward to carry so last week I bought another, better designed one. However when I got it home I realised it is quite a bit smaller than the one we already have and wondered whether I should return it, but left it open in the living room.... and every day since then my cat has got inside and spent the day asleep in it!
As he seems to find it comfortable, would it be unkind to use it even though it is a bit small for him? He is only ever in it for 10 minutes or so en route to the vet, never for long journeys as he is looked after at home when we are away. I guess I'm trying to avoid taking him in it to his next vet visit and being scolded by the vet!