Farmer Chris Green is counting the cost after three of his lambs were savaged by dogs.
Two of the lambs, which were born a fortnight ago, were killed and one was severely maimed.
The dogs, which were not wearing collars, got onto Mr Green’s land at Till Carr Farm, Lightcliffe, and attacked the lambs early on Monday morning.
“I came out to feed the sheep at about 7.30am and heard the dogs yapping and barking.
“I went round the back of the barn and I found the lambs - the dogs had gone for their throats.
“I’ve been up all hours with lambing over the past few weeks and I’m sickened by what has happened. It’s horrible to see animals suffering like this.
“I think the lambs are probably worth about £40 or £50 each to me.”
Mr Green managed to catch and restrain the dogs which were taken away by the dog warden.
“I don’t blame the dogs, I blame the irresponsible owners.
“I have had dogs running loose on my land before but this is the first time my sheep have been attacked.
“If I hadn’t come out at that moment I dread to think what would have happened.”
Mr Green believes the dogs may have been used for hunting in the nearby fields and had escaped from their owners.
The National Farmers’ Union has also appealed to dog owners and walkers to take care of their animals at lambing time.
The NFU livestock board chairman Charles Sercombe said: “The countryside is a beautiful place to walk in. However, it is a working environment where animals graze. So it’s important that people take care and are mindful of their surroundings so you can fully enjoy the experience.”
The NFU has joined forces with the Ramblers to encourage walkers to keep dogs on leads when walking in fields with livestock.
“In the spring it’s especially important for walkers to be sympathetic to farm animals rearing their young and give them space,” said Mr Sercombe.