They're used to saving hikers and climbers who get into trouble while out on remote moorlands and fells.

But when locals spent three days searching for a lost dog in scorching heat, mountain rescuers felt the need to step in with a thermal drone – finding the pet in just ten minutes.

The seven-year-old black brindled Staffordshire bull terrier had broken free of owner Andrew Charleton's grip during one of their walks in Rothbury, Northumberland, last week and vanished into dense undergrowth.

Mr Charleton, 63, was devastated as Jock had been a constant companion to him throughout his treatment and recovery from head and neck cancer.

Risking sunburn and heatstroke in temperatures of high 20C, a determined Mr Charleton was joined by his local community – including farmers and gamekeepers – to search for Jock by foot, bike and quad bike. 

Some even camped overnight in the hope that the animal might venture out as temperatures cooled.

But as hope for Jock's safe return dimmed, volunteers for Northumberland National Park's Mountain Rescue Team deployed a thermal drone – finding a hungry but unharmed Jock tethered to dense undergrowth by his lead.

Describing their reunion, Mr Charleton, a former area manager for Northumberland Water, said: 'Jock is not just a dog. He's my best mate who was by my side as we explored these moors together while I recovered from head and neck cancer.

'Jock never gave up on me – and I was determined not to give up on him. As soon as the mountain rescue team freed him, he bounced straight into my arms, and I cried as I hugged him.

'I don't know how he survived in that heat for three days with no water, no food. To find him alive and surprisingly bouncy is miraculous, he's one tough dog.'

Mr Charleton bought Jock as a puppy to help with his cancer recovery after undergoing 30 sessions of radiotherapy and six rounds of chemotherapy. 

The dog is well known in the local town for greeting people 'with a tail wag that resembles a helicopter taking off', he said.

'The bizarre thing is I must have walked within feet of Jock many, many times during my search calling his name and he never made a sound, not so much as a squeak,' Mr Charleton said.

'I think he went into some kind of primal state of fear where an animal's response is to stay as still and quiet as possible.'

Rothbury councillor Steven Bridgett was so moved by the groundswell of support for Jock in the initial days that he asked the mountain rescue volunteers, who are funded by public donations and usually rescue people in trouble on the county's vast, unpopulated moors and fells, if they would join the search.

They agreed, and a team of three – drone pilot Carl Hamilton, rescue team member Karl Wait and duty controller Andrew Miller – deployed their drone at 5am on Thursday, close to where Jock was last seen.

Will Close-Ash, spokesman for Northumberland National Park Mountain Rescue, said the drone could only be used in cooler hours, making the animal's body heat easier to detect. Within ten minutes, it had picked up Jock's location.

'We don't ordinarily help to search for missing pets, but we had the right people with the right skills in the right area at the right time,' Mr Close-Ash said. 

'It was lovely for the team to witness the emotional reunion between Andrew and Jock. With the heat and the length of time, no one expected a good outcome.'

Councillor Bridgett added Jock was a 'miracle of nature' to have survived in the heat without food and water.

Jock is said to be none the worse for his ordeal and is back exploring the moors – this time, with a tracker fitted to his collar.