The attack happened shortly after 10am on Thursday of last week.

Fortunately, someone was at the high school's agriculture plot in East Street at the time.

"I got a phone call from Graham Hunter, our agriculture assistant," teacher Anthony Carter said.

"He had just been over checking those sheep to make sure they had water. They were in the paddock on the other side of the creek because like everyone else, we are running out of feed.

"We believe the dogs came up along the creek. They just tore into them."

The injured sheep are poll dorset ewes and were given to the school by student Taylor Hawken's father Richard who runs a successful stud at Cookamidgera.

Mr Carter said when he arrived one ewe had been attacked and he thought she was dead.

"When I got closer I found she was alive, so we made an attempt to get her up," he said.

"As we were doing that, the dogs attacked the other sheep in front of us."

Mr Carter and Mr Hunter were approaching the dogs from different directions when the council rangers arrived.

"They arrived really quickly, we have tonnes of praise for those blokes," he said.

"The rangers managed to capture the dogs by calling them up, but by that time they had badly mauled three of our best sheep."

Local vet Daryl Elphick assessed the ewes and sadly one had to be euthanised.

The other two were treated with painkillers, anti inflammatories and antibiotics.

"They managed to survive the first night, which was a pleasant surprise," Mr Carter said.

"Unfortunately for us, they are expensive stud animals who were pregnant, but they would have lost their pregnancies from the trauma and shock."

The students have been enjoying a successful breeding program with Mr Hawken lending them rams to service their ewes.

"This year a ram that was offspring of the ewe that died came second in the Parkes Show," Mr Carter said.

"But an event like this kills the program because it kills the animals in the program."

Mr Carter said the students are heartbroken.

"They are animals that the kids have fed, haltered, groomed and prepared for showing," he said.

"They are very tame animals, they've all got personalities, the kids know their personalities and have nicknames for them."

Student Hannah Dickson is from a sheep farm herself.

"I think the hardest thing for us kids is that we know what's going on in this drought and to see something like this is just wrong," she said.

"If the dogs went on to some other poor farmers place and they were to do that there, it could ruin a farmer if it was his stud ram they killed."

Mr Carter said this is the fifth time stock on the agriculture plot has been attacked by dogs.

"I have no doubt that if we hadn't been here we wouldn't have any sheep left," he said.

"We have two flocks of sheep, merinos that we fatten up in the feedlot and sell and make money out of and our poll dorsets which breed stud quality lambs.

"Mr Hawken has gifted us six ewes, it's not every day a high school like ours is going to have something like that happen, it's a really generous gift.

"And he also provides us with rams, so genetically it's improving the flock every time we get a different ram.

"It would have been an absolute disaster for us if the ram that was here at the time had been hurt."

Mr Carter said the agriculture team are in discussions with the principal around attracting funding to put a dog proof fence around the area.

"We are going to have to spend about $150,000 otherwise this pretty effective agricultural breeding program we've got here we won't be able to do because we won't be able to have sheep here, we won't be able to have young cattle here," he said.

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