Dogs as ring bearers is so cute. You should probably have someone that can escort them out of the ceremony and watch them while the ceremony goes on rather than have them try and sit through the whole thing. Ceremonies are usually long and it would probably be a pain for them to sit through. Plus, it would really suck if they had to relieve themselves or went to mark somewhere on the stage. But I love the idea of them walking down the isle. If you had an outdoor wedding you could have a bone or some treats set up and they could sit there and do that, and then you don't have to worry about them peeing or pooping on anything other than grass.

I'll just ignore the "marriage is crock" issue. But marriage is all about compromise and considering your spouses feelings. For instance, if her fiancé wanted to have an ex that was still in love with him as his best man, then that's not ok and she should be able to explain her feelings on the issue and he should be respectful of that. I agree that it's his day too, and if he feels this seriously about it, then they need to come to a compromise. Maybe have a (human) best man walk the dog down the isle. But marriage is about compromise. He should be taking her feelings on the issue into account, the same way she should be taking his into account.