Pamela Hobart Carter imagines that dogs have a sense of humor, and that their jokes come from the same places their days do: lampposts, hydrants, passing Chihuahuas. The jokes she invents are silly and affectionate, with squirrels, poodles and a pun on "Take my fleas, please." Underneath the wordplay, the real humor is in the dog's routine: the same walk, the same sun rising and setting, the same outdoors.
The speaker clearly adores the animal. She admits we only "think he knows a few" jokes, but the wagging tail and jolly smile are enough to convince her. The refrain, "But isn't it wonderful again today?", repeats and turns the poem's gentle teasing into something sincere. The dog, it suggests, finds the ordinary new every time. The mood is warm, playful and a little wistful, and it nudges us to share that delight.