The Animal Path (畜生道, Chikushōdō) grants a Rinnegan user the ability of summoning various animals and creatures to aid it in battle. These creatures appear to be immortal, as they were killed and later summoned again. Worthy of note, summoning creatures through the Animal Path require no blood sacrifice or hand seals. The Animal Path can also summon people using hand signs, such as the case of Nagato's Paths and Konan. Tactics-wise, the Animal Path's primary role in battle appears to consist of overwhelming multiple opponents with a barrage of summons.
In the case of Nagato, having originally channelled the Animal Path through the corpse of a Fūma clan shinobi and then the corpse of Ajisai in life, the creatures summoned appear to have undergone the same modifications as his Paths of Pain, having chakra receivers embedded in their bodies. Nagato also tends to send the Animal Path first into battle to throw enemies off about the number of enemies they are really facing. As they also display the Rinnegan, the creatures serve as extensions of Nagato. During the Fourth Shinobi World War, Nagato used his summons for transport before being rejuvenated to move on his own power.
Buddhists believe that animals inhabit a different dimension separated from humans not spatially but mentally; an unhappy plane of rebirth which revolves around fear, instinct and survival of the fittest, suffered by those animals that work for humans and, above all, by those ignorant to what is happening to them.