Leigh Abbott, from Blackhall Colliery, last week walked up Ben Nevis, in Scotland’s Highlands, and was accompanied the whole way by his ageing chihuahua dog Alfie.
Despite being 12 years old and described by owner Leigh as “half blind”, the pair made it all the way to the top at 4,413 feet above sea level.
Leigh, 63, who had never climbed a mountain before, believes Alfie is the first and only chihuahua to have accomplished the feat.
They were staying at a nearby caravan park on a short break when Leigh decided to climb Ben Nevis.
Leigh, who worked as a coal miner for 20 years and is now a joiner, said: "I didn’t think I would be able to get up myself, but the dog went with us.
“I wasn’t going to take him but he knew where I was going.
"He was screaming the van down so I thought I would take him and fetch him back down when he’s had enough, but he didn’t.
"He just kept going and going.”
Leigh, who used to live in Hartlepool, completed the climb in nine-and-a-half hours.
Alfie walked the vast majority on his lead until blizzard conditions blew in near the top.
Leigh said: “It as Arctic conditions. It went from a beautiful day to complete whiteout at the very top.
"I couldn’t see 10 feet in front so had to pick him up and place him in a sling bag before he was lost forever.”
Just weeks earlier, three people died within a week on the mountain and 17 other got stuck on the peak, highlighting the dangers Ben Nevis can pose to climbers.
He added: “Me and my daughter Natalie did a bit of research and believe he is the only chihuahua to ever summit the highest mountain in the UK.”
However, it was not Alfie’s first experience of mountaineering, as Natalie took him up Helvellyn in the Lake District a few years ago.
Leigh now intends to take him on other climbing adventures to some slightly smaller mountains.