It would be adorable on an animal. The only caveat with dog names is that you have to be willing to yell the dog's name at top volume (when they get loose or at a dog park).
Mavourneen might be a bit clunky for that.
As an aside I once wanted to name a dog Huck. But then I thought about what it would sound like if I yelled it. *UUUCK! Hmmm, not so great...