Ollie, who belonged to Penny Kirby, of Wasdale Mountain Rescue Team, has died, aged nine.
The border collie was full of character and was a very successful rescue dog for seven years.
He was involved in more than 80 call-outs and was instrumental in finding Jasper the dog, who went missing last November and sparked a major search and social media appeal before being found.
Mick Guy, the treasurer of Lake District Mountain Rescue Search Dogs, said: “You talk to any search dog handler who’s either had to have their dog put down or it’s died suddenly, and it’s like a death in the family because it has become so much a part of your life.
“However much you are prepared for it, it hits you like a ton of bricks. It’s really, really tough.”
Mr Guy estimates dogs will cover the same ground as around 40 people while on searches and are particularly instrumental on night searches.
Training mountain rescue dogs can take up to three years or even longer with a new handler.
There are 15 rescue dogs spread across the mountain rescue teams in Cumbria and Ollie will not be easy to replace as the Wasdale team has to wait for a handler to come forward.
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