She has reported the incident, which they believe happened between 4pm and dark on Sunday, to Carterton police.
The financial loss, the distress it causes the animals, the impact on the lambs when ewes are stolen, and the fact they have done everything they can to stop it has left her frustrated.
"If we could find this person we'd shoot him, it's like if somebody kept coming and stealing from your house."
She said the loss comes after an already hard year, as the farm lost several lambs in the last snow.
Tyneside farm manager Fred Kendall, who found the dead sheep, said he's angry, particularly because it is the second time it's happened this year.
"I can't sit out there on the hill and watch them all night. This sort of thing has gone on too long ... We're going to have to take things into our own hands, I'm sick of it. I don't know what you do when you've had enough."
Masterton police Senior Sergeant Carolyn Watson said theft and sheep rustling is happening in all rural communities throughout New Zealand.
She said although it was an issue in the district around June or July, she had not noticed an increase in incidents since then.
"What we need is for farmers to contact us if they see any suspicious vehicles or particularly people on their land and if they could try and obtain registration plates."