The Australian RSPCA has called in a champion shearer to trim a heavily overgrown sheep found wandering in woodland near the capital.

A bushwalker spotted the sheep near Mulligan Flats, just outside Canberra, and called the RSPCA, which mounted a rescue mission on Tuesday.

Tammy Ven Dange, the chief executive of the Australian RSPCA, said five staff members were needed for the job.

It appeared the sheep had become lost from its herd. Ven Dange said merino sheep were bred to grow wool and could suffer infections or flystrike if they were not regularly groomed.

The sheep had clearly not experienced much recent human contact. Ven Dange told ABC radio: “We are concerned about him going into shock through this whole process. We are going to have to sedate him before we shear him.”

Of the sheep’s excess bulk, Tammy Ven Dange, from the Australian RSPCA, said: ‘I don’t think anyone is going to want it.’ Photograph: RSPCA/AFP/Getty Images

The fleece will be weighed to see how it compares with other sheep that managed to evade shearing for extended periods.

A fleece from a New Zealand sheep called Shrek, which managed to avoid being shorn for more than six years by hiding in caves and subsequently met the then New Zealand prime minister, Helen Clark, is thought to have been the world’s heaviest at 27kg (4st 3lb). Shrek died in 2011.

Shaun, a sheep from Tasmania that had gone on the lam, had a fleece that weighed 23.5kg when shorn.

Shaun, a sheep from Tasmania, shows off its fleece weighing over 20kg. Seen here in 2014 before being shorn. Guardian

In order to give the latest sheep expert attention, a call was put out by the RSPCA on social media. Ven Dange said it was fortunate that the multiple shearing champion Ian Elkins answered the call. Asked whether the fleece could become a top-quality jumper, Ven Dange said: “It’s pretty disgusting. I don’t think anyone is going to want it.”