In Pre Colombian myth Quetzalcoatl and his twin Xolotl is Venus, the Morning and Evening Star and the protector of all life, all living things, and conqueror of Death.

After the great flood, all of Earth was barren and empty, no humans toiled or hunted and their image was buried deep in the underworld Mictlan and guarded by Mictlantecuhtli and Mictlantecihuatl. Quetzalcóatl and Xolotl through great trials carried the Living Bone from which all man is made from Mictlan to Heaven. And from Heaven, by the help of the Gods, Man was resurrected to live again on Earth.

To prevent Man from ever getting lost again in the deepest dark of the underworld, Xolotl created a protector in his own image made from a sliver of the Bone of Life. This protector is gifted with human abilities because it is made from the Bone of Life and some heavenly abilities as into the sliver Xolotl blew his knowledge of the Heaven and the Underworld. And Xolotl gave his gift to Man with the instruction to guard it with his life and then in exchange it would guide Man through the dangers of Mictlan, the world of Death, and towards the Evening Star in the Heavens.
This guide given to Man from Xolotl himself is the naked dog, the Xoloitzcuintle.

In the glory days of the Fourth World, before Earth as we know it today, the Gods came down from the Heavens to walk amongst the people. When they got ready to leave again, a small girl cried relentlessly holding the hands of the Twins, Xolotl and his brother, wanting them to take her with them as they left. Taking pity of the girl, Xolotl took a clay flute and blew the life force into it. As it came alive it looked like him, like if it was Xolotls baby brother. He gave the little dog to the girl and told her: When it is your time to leave Earth, my little brother will safely guide you home to me. This was the first Itzcuintle and his descendants to this day will guide us home to the Heavens when our time come.  

When you die the great darkness come to swallow your spirit and you have to live in the land of the dead Miquiztli. To avoid spending endless time in the clutches of Death, you have to descend through the Mouth of the Jaguar and cross the big water that is the leftover from the big flood and has no direction or horizon. Then get through each level of dead worlds and pass through the gate of living rock. But to get through that is difficult. After passing through the gate you are free to roam the heavenly realms.

The great darkness does not want to swallow spirits from warriors slain in honest battle and women who has no breath at childbirth, those can go directly to the stars. The naked dog will carry the spirit of the children that die without having lived so they do not go to the shadow below unprotected.

The only living thing that walk safely in the shadows is the one that carries the spirit of Xolotl, the twin of Quetzalcoatl that bring the light of day to us every morning. Therefore the best is to have a dog with you when you die and hold on tight to get through the shadows to the light. The best dog is said to be a naked dog with red skin, as the red of the Evening Star is the light reflecting of the Sun, thus the red dog will light your way to be reborn at dawn.

Because the evil Cizin kept spirits locked up at the deepest chambers in his kingdom, Itzama gave the blessed people Itzcuintle to move through Cizin's realm as swift as the Sun move through the shadow at night without resting.

It has been told a great dog has found his way from the underworld by getting the living rock to push him to the surface. With a mighty lightning bolt he was born out of the great volcano and where he washed off the memories of the shadow is now a lake called Xolotlán in Nicaragua. This dog and all his ancestors is believed to speak the language of the gods (and the 13th heaven) and forever carry the burned skin he got from the volcano.