It's an unbreakable bond between man and dog and how they came into each others lives is remarkable.
Zak Anderegg was exploring a canyon in Arizona when he came across a dog in a most unlikely site. It was stranded 350-feet beneath the Earth's surface, and was all skin and bones.
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Anderegg told INSIDE EDITION, "He was so weak and so frail. He was as close to dead as any animal I have ever seen, and yet, still alive."
He gave the puppy food and water. Then, he climbed out of the canyon and returned with a pet carrier he got from a local animal hospital. The puppy was still there, lying on a blue towel Andergg had left for him.
He put the puppy into the pet carrier, and 30 minutes later, made it to the top unscathed.
The dog looked emaciated when it was rescued. Anderegg named his buddy Riley.
That was four years ago, and now, Riley today is thriving after being brought back to life.
His wife, Michelle, is thrilled.
She told INSIDE EDITION, "He is the best dog in the world. He is happy, he is go-lucky, he is affectionate, he is sweet."