What is Kazak?

Kazak is a ferocious dog that stalks and attacks the narrator during the novel's epilogue. The narrator claims that, in earlier drafts of the novel, Kazak had been a more-significant character. The narrator removed Kazak during the editing process; but such a mean-spirited dog is not easily obliterated without trace. Thus when the narrator becomes distracted, Kazak sneaks back into the narrative and launches a surprise attack. The narrator easily eludes the dog and Kazak promptly disappears again.