Former army reserve Mark Douglas, 37, succumbed to the condition, known as the human form of mad cow disease, earlier this year.
There are no clues as to how he contracted the condition, which claims the lives of fewer than 100 people in the UK per year.
Laura Baird, his partner of 20 years, said: “We thought it can’t be CJD – he was the wrong age group and all sorts but that was what he had. It was a massive shock to us.”
Mark, who was born in Morningside, had spent more than 20 years working as a trainer before moving to rural Dumfries with Laura to found Chamfrom Stud Farm.
Laura, 40, originally from Loanhead, said: “The day he was diagnosed I had 29 horses in the stud and I just stood in the barn and thought, ‘What am I going to do?’
“He was very confident, very capable. There wasn’t anything he couldn’t turn his hand to and he would always give anything a go.
“He was very loyal to his friends. He was by all accounts an exceptional horseman and a good bloke.”
Mark was first rushed to hospital on December 23 last year after falling ill but doctors could not initially establish what was wrong.
After spending Christmas wracked with anxiety, he was finally diagnosed with Creutzfeldt-Jakob disease (CJD) on January 4 – a degenerative condition which had a variant form that was linked to mad cow disease. The illness is currently untreatable and Mark died on January 20.
His cousins, Lynne Riddell, 42, and Karen Muir, 39, will take on the UK’s biggest obstacle course in his memory to raise money for the Alexandra Unit at Dumfries and Galloway Hospital, where he spent his final days.
Along with their respective husbands, Barry, 43, and David, 33, the sisters will take on Gung-Ho!, a 5km inflatable obstacle course held on The Meadows in June.
Mum-of-two Lynne, from Bathgate, said: “We were all going to meet at Karen’s wedding this year but sadly he never got there. After he died we decided we were going to do something in his memory and then we found out about Gung-Ho!.
“Hopefully we can raise a good amount of money to help make a difference.”
Laura said Mark would be proud of his cousins for taking on the challenge.“I think it is a lovely thing for Lynne and Karen to do. The people who looked after him were absolutely outstanding.”
What is CJD?
CREUTZFELDT-Jakob disease (CJD) is part of a group of rare, fatal brain disorders which occur when a particular protein starts to behave abnormally.
When this protein folds into an unusual shape it can damage brain cells, causing a rapid decline in thinking and muscle movement.
CJD kills around one or two people in a million each year worldwide. The illness can be passed down through family members, although most cases occur with no explanation.
A variant form of CJD sparked panic in the 1990s as scientists linked it to eating infected beef from cows with bovine spongiform encephalopathy (BSE) – or mad cow disease.