IN 43 years of farming, Wes Titley has seen most things, but was stunned when he discovered mice living in the wool of his sheep.

Mr Titley, 58, says he is constantly pulling nesting mice out of his Poll Merino sheep as the rodent plague continues to spread across the state, Adelaide Now reports.

"You get out at night and struggle to put a foot on the ground for all the mice," the farmer from Sherlock, east of Tailem Bend, said.

All of his 10 show sheep had rodent damage.

"They had wee and poo in the wool and the mice tear around in the wool in a circle and matt it up, they mess it up and it gets discoloured," he said.

"They are trying to live in the fleece because it's nice and warm. I check the ewes every two days but there'd still be dead mice in there."

And Mr Titley said while mouse numbers in the paddocks had dropped off, things were getting worse inside the shed where his show sheep sleep. 

"In the shed the mice have now started to bite the sheep and that can be pretty uncomfortable for the sheep," he said.

"There's nothing you can do but use poison."

Mr Titley said farmers were resilient and would work through the plague, but it had been a trying time.

"It's been pretty testing," he said. "I've spent quite a bit of time picking poo out of sheep. I literally clean the sheep up with my fingers. You rehabilitate them as best you can."

Mr Titley said he wasn't the only farmer with the problem, with fellow competitors at the recent Bendigo Show also complaining of having mouse-damaged sheep.

"The mice are a nuisance but they're not crushing us. They are a distraction," he said.

Mr Titley was hopeful of having his sheep in good condition in time for the Royal Adelaide Show in early September.

Read more on Adelaide Now.