Lakota Native Legend

When the world was created, First Man and First Woman struggled to stay
alive and warm through the first winter. First Dog struggled also.

 Deep in the winter, First Dog gave birth to her pups. Each night, she
 huddled in the brush of the forest, longingly watching the fire which kept
 First Man and First Woman warm.

 First Winter was severe, so cold that First Dog dared not leave her pups
  to  search for food to fill her own belly, fearing that her pups would freeze
  to  death in her absence. She curled around them, but the wind was bitter. Her
 belly shrank with hunger, and soon she had no milk. The smallest pup
 perished, and First Dog felt her own life draining away as she struggled
  to   care for the remaining pups. Fearing for the fate of the others, she knew
 she had no choice but to approach the fire and ask First Woman and First
  Man   to share their food and the fire's warmth.

 Slowly, she crept to the fire and spoke to First Woman who was heavy with
 child. "I am a mother," said First Dog, "and soon you will be a mother
  too.
 I want my little ones to survive, just as you will want your little one to
 survive. So I will ask you to make a pact."
 
  First Woman and First Man listened. "I am about to die. Take my pups. You
 will raise them and call them Dog. They will be your guardians. They will
 alert you to danger, keep you warm, guard your camp, and even lay down
  their life to protect your life and the lives of your children. They will be
 companions to you and all your generations, never leaving your side,
 as long as Mankind shall survive. In return, you will share your food and bring them inside for companionship and
 the warmth of your fire. You will treat my children with love and
  kindness, and tend to them if they become ill, just as if they were born from your
  own belly. And if they are in pain, you will take a sharp knife to their
  throat and end their misery. In exchange for this, you will have the loyalty of
  my children and their offspring until the end of time."

 First Man and First Woman agreed. First Dog went to her nest in the brush,
 and with the last of her strength, one by one, she brought her pups to the
 fire. As she did so, First Woman gave birth to First Child, wrapped her in
 Rabbit skins, and nestled First Child among the pups by the fireside.
  First Dog lay down by the fire, licked her pups, then walked away to die under
  the stars.

 Before she disappeared into the darkness, she turned and spoke once more
  to   First Man, "My children will honor the pact for all generations. But if
  Man breaks this pact, if you or your children's children deny even one Dog
  food, warmth, a kind word or a merciful end, your generations will be plagued
  with war, hunger, and disease, and so shall this remain until the pact is
  honored again by all Mankind." With this, First Dog entered the night and returned in spirit to the Creator.