Chris the sheep fleeces world record

He's the shear-leader of the woolly pack.

Chris the sheep has broken world records after having 40.45 kilograms of fleece trimmed in a hair-raising, life-saving surgery on Thursday.

Spotted by a bushwalker in the Mulligans Flats area near the NSW-ACT border, Chris was carrying such a heavy load that animal welfare experts feared he wouldn't make it through the summer.

He was brought into the RSPCA's Canberra facility and trimmed by champion shearer Ian Elkins, who answered the organisation's call for help.

Mr Elkins believes he cut seven years' worth of growth - double the sheep's body weight.

"It's amazing it's survived all these years out in the wild," he told AAP.

The record-breaking weigh-in confirmed Chris had more than bleaten - so to speak - the competition.

He pipped Shaun from Tasmania (23.5kg) and New Zealander Shrek (27kg) - fellow rogue sheep who evaded the shearing shed for years.

"It's unlike anything I've ever seen," Mr Elkins said.

Chris was feeling fine after his makeover.

"He's gone from a very shy sheep to one that wants cuddles now," RSPCA ACT boss Tammy Ven Dange said.

"He's looking really good right now."

But Chris wasn't available for post-cut photos.

"He might be drugged up still," Ms Ven Dange joked.

As for his future, Chris is up for adoption, but it will be on a first-in-first-served basis - and someone's already reserved him.

And his fleece? It would probably end up in a museum, Mr Elkins reckoned.