The speaker announces, almost cheerfully, that they are a dog, and the title's pun on "dogged" hints at what that means: stubborn, repetitive persistence. The dog keeps coming back to "kill / that tip of the tail again," chasing something that is part of itself and can never be caught. Then it digs a hole deeper, as if the same pointless task can always be pushed a little further.
The second stanza turns inward. "Trepan" means to drill a hole in the skull, so the speaker seems to be boring into their own "never mind," a phrase that sounds like a shrug, a thought brushed aside. The poem suggests that this dismissed, half-forgotten part of the mind is what the speaker keeps digging at. Yet the ending is oddly content: "My mist is rich." The vagueness and confusion are treated as valuable, not as a problem. The mood is playful, strange, and a little obsessive, with a sense that wandering in circles can be its own reward.