Const. Jason Michalyshen said a forensic analysis by two pathologists has confirmed the bones are from an animal.
Volunteers searching the banks of the Red River came across the bones earlier this week. The group is combing the shoreline and dragging the bottom of the river, searching for anything that might bring closure to those searching for loved ones.
A blood-splattered pillowcase, a bloody rug and a set of dentures have also been turned over to police.
"We're absolutely taking the search of the Red River very seriously," Michalyshen said. "When items are located — and items will be located — we're going to respond as quickly as we can."
The group formed after the discovery of the body of 15-year-old Tina Fontaine last month.
She had run away from foster care and her body was found wrapped in a bag and dumped in the river. Her death has been ruled a homicide, but police have not made any arrests.
The case touched a nerve across the country, prompting renewed calls for a national inquiry into almost 1,200 missing and murdered aboriginal women.
Bernadette Smith, whose sister Claudette Osborne disappeared in 2008, spearheaded the search effort because she said families searching for answers can't sit idly by when the river might provide a clue. The group has hundreds of volunteers and several boats to drag the bottom of the river in search of more bodies.
Police have been sharing their expertise about currents with the group and say they will have a staffed police boat on the river when volunteers go out to dredge. The group plans to continue searching until November.
— With files from CJOB.Suggest a correction