A dog attack left dozens of sheep dead this week at a Eugene-area farm, spurring an Oregon State Police investigation.

Forty-one ewes and newborn lambs were killed in the attack, according to the Oregon Department of Fish and Wildlife. The Oregon State Police confirmed it’s investigating the killings.

Michelle Dennehy, a fish and wildlife department spokeswoman, said two different-sized dog tracks were found in the pasture where the sheep were killed, meaning at least two dogs were involved in the attack.

The dogs responsible had not been found as of Wednesday, according to Capt. Tim Fox, a state police spokesman.

State fish and wildlife officials in Lane County hear of domestic dogs or feral domestic dogs attacking livestock once or twice annually, Dennehy said. A mass killing by domestic dogs is uncommon, however.

Dennehy didn’t know of any other recent reports of dogs attacking livestock in Lane County.

KVAL, a Eugene television station, reports the attack was discovered Tuesday and spared 12 sheep, which will be sold this weekend.

Leslie Anthone, who owns the sheep with her fiancé, told KVAL she wants the dog owners to come forward. “Someone on Clear Lake Rd owns dogs that came home this morning covered in mud and blood,” she wrote on Facebook.

"Everything that my whole family has helped me work for, gone," she told the news station.

-- Jim Ryan; jryan@oregonian.com; 503-221-8005; @Jimryan015

Visit subscription.oregonlive.com/newsletters to get Oregonian/OregonLive journalism delivered to your email inbox.