A farmer has urged dog owners in Richmond to keep their pet on a lead around livestock.
The appeal comes after he suffered the loss of a second sheep in as many weeks.
Mark Kirby farms at Hollies Farm, near Hudswell, but also has land near the Gallowfields Industrial Estate in Richmond.
Around two weeks ago he found a young tup lamb dead in a field near the Gallowfields.
He then found a ewe pregnant with two lambs dead at the weekend.
Although neither animal appeared to have been bitten, both were close to a footpath popular with dog walkers.
A dog toy was also found beside the dead ewe.
Although Mark did not lose any sheep to dog worrying last year, he has had regular problems in the past.
He said: “I was up there on Saturday and there was everything was fine, but I went back and found the Suffolk cross ewe on Sunday morning just near the footpath.
“Dogs don’t need to bite the sheep — they can just chase them until they’re exhausted.”
Mark believes the dog walker left the toy behind after panicking when the sheep died.
Mark added: “Please, please if there’s sheep in the field keep your dog on a lead, especially if it’s after Christmas when they might be pregnant.
“If you’re walking on these fields it’s another five minutes and you can be on the gallops and you can do what you want.
“I don’t want to spoil anybody’s fun but this is my livelihood.”
The incident has been reported to North Yorkshire Police.
Anyone with information should call 101.