My guess is that the partner that was supposed to be watching the dog, wasn't watching, and the dog ran off, or was hit by a car. They saw a large gull flying around and concocted the cover story, not realizing how utterly preposterous it was.
OR somebody just leaned over the fence and nicked the dog!!! Dog theft - especially of the smaller breeds - is rife and they can quickly be 'offloaded', no questions asked, on gumtree/preloved/pets4homes etc.....there'll always be somebody who will buy a dog cheap and not be bothered about proper documentation :C Decent owners NEVER let their dogs out of their sight! :C
But comments like small breeds being nothing but rats is way out of line....it's the equivalent of saying all germans are nazis and all gay people are sick freaks....I've known a few in my life who've had sensible owners and they have been the loveliest dogs you could ever meet... not yappy or snappy or any of the other adjectives ignorant people use to describe them :C You'll usually find the ones who give the breed a bad name are ones owned by bimbos with fake nails, too much fake tan and carry them around in bags!