Anyway, one quick anal probing later, Boo was given a diagnosis. The verdict: he is constipated and needs to add more fiber to his diet. So basically, he's American.
The vet's advice was to put him on a low-carb, high-fiber diet, which will "help with his weight, too." I lost count of the number of times she incorporated, "he's a big boy" into a sentence. We get it, okay? Some of us don't have as fast metabolisms as others. It's genetics!