Using some British slang to describe his tattered companion, Mulligan condescendingly exclaims, "Ah, poor dogsbody!" A dogsbody is an individual at the bottom of the institutional pecking order who is assigned the boring, menial, or unpleasant tasks that no one else wants to do. Close American equivalents are “gofer,” “grunt,” and “drudge.” But Stephen takes the phrase literally, sparking a series of meditations on dogs' bodies.
Mulligan means the "poor" part literally enough. He couples his ribbing with offers of charitable assistance: "I must give you a shirt and a few noserags. How are the secondhand breeks?" But Stephen, who is all too familiar with lice crawling on his body, has his own way of hearing "dogsbody." Soon after Mulligan gives him the name, he thinks, “Who chose this face for me? This dogsbody to rid of vermin."
Brooding on the equivalence man = dog, the narrative will hatch numerous connections between the bodies of dogs and those of men. And since the Christian doctrines of incarnation and transubstantiation assert connections between the bodies of men and the spiritual presence of God (as in Christ's "This is my body you eat"), a further dyslexic equivalence is implied: dog = god. In one passage of Circe, backward writing turns God into Dog, and "Dooooooooooog!" back into "Goooooooooood!"
In Proteus, Stephen contemplates two dogs on the beach, one living and one dead. Like the living dog, he pisses in the open in this episode, and he thinks of the animal on remarkably equal terms: “Lord, is he going to attack me? Respect his liberty. You will not be master of others or their slave.” If dogs are not essentially different from men, then their mortality should not be thought about in fundamentally different ways. The dead dog in Proteus anticipates the drowned man in Dublin Bay, whose decaying body Stephen contemplates at the end of the episode.
When the live dog encounters the dead one and recognizes a "brother," Stephen feels kinship too: "Dogskull, dogsniff, eyes on the ground, moves to one great goal. Ah, poor dogsbody! Here lies poor dogsbody’s body." The great goal recalls Mr. Deasy’s philosophizing in Nestor, but Stephen does not see life moving toward a Christian or Hegelian "manifestation of God." It is moving toward death, decomposition, and reconstitution: "God becomes man becomes fish becomes barnacle goose becomes featherbed mountain. Dead breaths I living breathe, tread dead dust, devour a urinous offal from all dead." If this reasoning affords no exit from the material universe, it nevertheless does allow for the possibility of spiritual presence within material beings: animals, men, and such divinity as may exist all swim in the same circle.