CORVALLIS, Ore. - Early tests by Oregon State University scientists indicate that four dogs that recently died outside a Marion County woman's home were poisoned.

Doctor Christiane Lohr, an OSU veterinary pathologist, found a green-colored grain inside three of the dogs' gastric contents. The grain looked similar to gopher bait - laced with deadly strychnine. Two of the three had large chunks of pork in their stomachs as well, she said.

"These are somewhat unusual findings," Lohr said.

Lohr, the university's authority on poisoned animals, is studying three of the four dogs found dead on Valarie Bakers' land near Silver Falls State Park over the weekend.

Her dog Snowy died Friday while Mickey and Dreamer died on Saturday.

Baker found a fourth unidentified dog laying dead on a new blanket not far away. She has no idea what killed them but suspects foul play.

"We think it's something intentional," she said. "We feel like they're just dead for somebody's sick pleasure."

Lohr hopes to determine whether that's the case at the OSU diagnostic lab. The contents of the stomach, the condition of the vital organs and the breakdown of tissues could all indicate different killers.

"It makes me wonder if somebody did put out a combination of that gopher bait and the meat," Lohr said.

Final tests will determine exactly what killed the dogs. The studies conducted at OSU indicate it was poison, probably strychnine.

The state Department of Agriculture and Marion County Sheriff's Office are investigating the case.

Toxicology tests on the stomach contents are being conducted at Michigan State University.

One of the dogs had three handfuls of the gopher strychnine bait in its stomach. It's unclear how someone would get that much poison. People need a license to buy such bait.