I've always thought the parks were missing the boat by not offering more merchandise for pets. Pet lovers miss their four-legged friends on vacation, and want to bring them a piece of the magic!
I know Disney did some semi-cheesy printed nylon dog collars a few years ago, not park specific, but something higher end (nice leather, embossed with Mickey heads, perhaps?) would be most welcome.
I compromise by bringing a new charm home for my beloved pug's collar each trip. There's a huge variety of sterling silver ones to choose from, and they fit just fine if I place them directly onto the split ring that holds her I.D. tags. So far she has Tinker Bell and Minnie (she wears one at a time).