If you have a weak spot for small white dogs, you can't miss the Maltese. (notinthedoghouse.com)
For others among the really cute small white dogs, this list is perfect! (pethelpful.com)
Example: If you've found a female white toy poodle with brown eyes that's been spayed and has a missing front tooth, simply say «Found small white dog». (lenoircountyspca.org)