There was a story in Argentina about five years ago. The family took a pregnant dog from the street. The new pet was called a Negrita.
The dog was exhausted, infected with parasites, so the new owners spent a lot of effort just to wash and cure it. Soon the Negrita had puppies. When the kids grew up, new homes were found for them, and the Negrita was sent to the relatives of the couple who lived in another city. The couple who picked up the dog from the street was elderly, they were worried that they would not be able to take care of the animal, so they found another home for her.
The dog lived with the new owners quite a bit, once simply disappearing without a trace. The Negrita was searched all over the city, but the search was in vain because she ran back to the people who saved her from life on the street.
When the dog returned, she was hungry, and there were traces of many wounds on her paws. An elderly couple fed the animal, washed her from road dirt, and treated the cuts. Exhausted by the road, the Negrita slept for two days.
The couple told their relatives that the dog was found and this time they decided that they would not give the dog to anyone, but would take care of her as long as they had the strength to do so.