Five years ago, Don Callahan rescued an abandoned and abused dog at an adoption fair at the Detroit Zoo. In January, that same dog returned the favor.

"He means the world to me, he is my buddy, and he saved my life that night," said Callahan.

It was part of their daily routine. Callahan is a retired Southfield police officer. He took Wyatt out for his walk around 7 p.m., but that night, Wyatt was the one watching over Callahan.

"The last thing I can remember is I reached out for the wall down by Fairway Condos down there, that's the last thing I can remember until I woke up in the intensive care unit," said Callahan.

Callahan is a diabetic, his blood sugar became too low. He collapsed on the sidewalk. No one saw his body, but Wyatt never left his side and never stopped barking. That is when police received a call.

"People call the police for all kinds of things...annoyed by barking dog that night...they don't know how important that phone call was," said Callahan.

Everyday, Callahan is grateful that someone thought Wyatt was a nuisance that night.

"The doctors told me I would not have survived, if it had been another 20-30 minutes before I was found," said Callahan.

Callahan still does not know which neighbor made that call to police. Since his fall, Callahan has been recuperating at home. He recently got a new diabetic monitoring system that lets him know when his blood sugar is dropping. Still, Wyatt is never too far away.