Two categories of animals are studied in the epic poetry of Lucan, Statius and Silius, categories which are defined regarding their stylistic and dramatic function. Either animals take part in the numerous similes, in particular in the descriptions of singular warriors or sportsmen, or they interfere during dramatic action, the main action which they can slightly modify or a secondary action, as premonitions or symbols. By the example of the snake, which is symbolically ambivalent, it is possible to show this function in the poem's narrative rhythm, as it stresses the developement of action and accompanies its stages. The two types of occurrence deal with an experience of limits and search of truth, far beyond immediate appearances. Philosophical truth and human limits through the confrontation between different fields of life, in epic actions where humanity is threatened in its very definition. Truth as well of a poetic and ideological project, which is, for Silius, whithin the limits of myth and history. Animals, from that point of view, permit, often by allusions, the action to settle and to become richer with literary, symbolic, mythological and historical implications, which make the complexity of epic manner.