Plato's reference to dogs in different passages of the Republic is more than a mere embellishment; it also serves to defend important political theses (335b8; 375e; 376b; 416a; 440d; 451c-e; 459a; 459b). The purpose of this article is to reveal some of these theses and to defend the author's choice of the dog, among other animals, to characterize the figures of the guardian and of the philosopher. The text discusses the analogy presented in the Republic according to which the natural disposition to guard (someone or something) is the common element shared between a puppy and a young man from good descent. The article focuses on the dog's role - descending from a wilder and more beastly animal, the wolf - as that of being able to synthesize fierceness and gentleness through learning and domestication.