MONTY the Labradoodle really was man's best friend after rescuing his owner, Maurice Holder, when a fall knocked him unconscious.
The mixed breed dog stayed with Mr Holder, 73, when he fell 40ft down a ravine and blacked out as the waters rose around him.
Mr Holder, who had suffered six broken ribs and a head injury, regained consciousness 15 minutes later to find his loyal pet watching him.
The 11-year-old dog then left him to safety up the bank of a river in Cornwall before raising the alarm at a nearby pub.
Monty barked until he caught the attention of a customer who helped Mr Holder to his car and called an ambulance.
Mr Holder said: "We were walking along the river. I was literally standing still with my hands in my pockets listening to the silence and the sound of the river, when suddenly the earth moved.
"There was a tremendous rumble and the whole lot came down with no warning, nothing.
"I just went down – it felt like going down in a lift really fast. I fell about 40ft and landed on a great slab.
"I don't know how long I was out for, it could have been around 10 to 15 minutes.
"I woke up and the water had come up to my chest and I was aware that I was bleeding from my head. I looked around and saw Monty sat next to me."
The grandfather-of-eight said he knew the only way out was to go back up the steep riverbank.
Mr Holder, a retired sales director, was told that the time frame was critical due to his head injuries and his accident could have been fatal.
He added: "I find it a nice area as you don't get hoards of people there. But after the fall I had six broken ribs and I thought I could be here for hours or days.
"Monty got me to level ground and then I just lay down to get my breath back and as I did Monty ran away.
"He came back around 15 minutes later with a nice gentleman who helped me back to the car and an ambulance came."
Maurice was taken to hospital where they treated him for two days for head injuries, broken ribs and cuts and bruises to his back.
He added: "I was a bit of a fright with blood from my head down to my waist. I think the broken ribs were more painful than anything else.
"I have been back a couple of times and when I saw where it happened and how far I fell I couldn't believe it.
"Monty is absolutely the perfect pet. I wouldn't say he is always the best behaved but he is loyal and that is what matters – man's best friend."