Physiology

"Lucario is a bipedal, jackal-like Pokémon, with fur that is predominantly blue and black. It possesses a short, round spike on the back of each forepaw, in addition to a third on its chest. Lucario's snout and ears are longer than those of its pre-evolution, Riolu. It possesses cream-colored fur on its torso, and blue fur on its thighs that resembles shorts. Like its pre-evolution, Lucario stands on its toes rather than on its entire foot. It has developed four small black appendages on its head, which rise when Lucario reads or manipulates aura." (Excerpt from Bulbapedia)