A Lake Hayes farmer who lost 13 sheep in a dog attack this week says the financial cost is bad enough, but the stress and worry it causes him and his wife are worse.

Jared Hutton found nine ewes and two lambs dead on his leased 150ha property at the Threepwood private rural subdivision on Monday, and put down two more injured ewes on Wednesday.

It was the fourth year in a row dogs had killed sheep on the farm, always during lambing, Mr Hutton said.

Although each dead animal cost him and wife Katie about $140, they could live with that.

"It's actually the stress and the workload it creates from trying to fix all this.

"It's the dismothered lambs, the injured animals and just the stress of walking up there and finding that.

"We're at the stage now where we're thinking about getting rid of our sheep and going to cattle."

The couple lost 35 lambs in a single attack in 2016, and 27 more in two attacks last year.

Mr Hutton said he would shoot any dog he saw roaming on the property.

As ewes had been attacked, he assumed the dog responsible was large.

It was unlikely to belong to a Threepwood resident, who were all highly aware of the issue.

He suspected it was visiting the area during the day, and possibly belonged to a tradesperson.

There were plenty of dogs in the district that were "not trained and not looked after", he said.

"You don't have to walk on many tracks around the district to see a wayward dog."

Many dog owners just assumed their pet would never attack farm animals.

"I don't think a lot of town people realise what their dog is capable of."