These are very puzzling dog images, from Coconino National Forest cliffs at the Palatki Heritage Site in central Arizona. Two of the three dogs have exceedingly long tails, one of those two has a dog head at the end of the tail.
This must represent some sort of supernatural dog with a serpent for a tail, perhaps the parents of the "mortal" dog with the normal tail strolling before the pair.
It's a stretch, but there may be some connection with a Central American myth of a dog who taught secrets of the gods to humanity, and so had its head and its tail turned around, losing thereby the power of speech, having only the ability to wag the tail when it wanted to communicate something useful. Conceivably this pictograph represents some variant of that folklore, in which the tail that became the head gained the power of speech.
More likely it represents a chimarae figure part dog part serpent, either signal to a shamanistic transformational religion, or a monster dog such as Native Americans further to the southeast believed to be the source of drownings, a dog-dragon given offerings of dogs in order to win its protection around water. If this image relates to this alternate myth, then the "normal" dog walking before the pair is the offering.