I wouldn't. I know some pets mean a lot to their owners, but it's just another thing that must be taken care or and that could go wrong. I know of a lady that spend something like $500 on her dog's birthday party...
I love my dog and cat but would not have them at any formal function, definitely not a wedding. My cat avoids people he doesn't know well. My dog is more social but would be overwhelmed by a large group.