We should not really be surprised by the news that dogs experience emotions, or that there are some canines prone to pessimism and others of a more naturally sunny nature.
An empire of fiction has been built on the notion that man's best friend has a relatively sophisticated inner life. Consider the loyalty of Greyfriars Bobby, the helpfulness of Lassie, the energy of Rin Tin Tin, the restlessness of the Littlest Hobo, the bravery of Beethoven and the crime-solving abilities of Scooby Doo. And where would Wallace be without his Gromit? Feline anthropomorphism, by contrast, is a much less developed animal.
Consider also the number of dog-based figures of speech we apply to our own lives: "dog tired", "it's a dog-eat-dog world", "dogged", "dog in a manger". We constantly see human characteristics in our hounds. And now, it appears, with good reason.
Vindication for authors and scriptwriters then. But the research also has the slightly disturbing implication that those rich folk who have been spending money on psychotherapy for their pets might, despite the scoffing of the rest of us, have been barking up the right tree all along.