The Ontario Society for the Prevention of Cruelty to Animals is investigating a farm north of Mount Forest, Ont., where hundreds of rabbits appear to be running free and unattended.

A neighbour spotted the rabbits on the property in Holstein, about 90 kilometres north of Kitchener. Upon further inspection, she discovered more than a dozen rabbit carcasses and the smell of feces coming from inside a barn on the property.

Carol Gravestock, who posted video of what she found on Facebook, told CBC Kitchener-Waterloo the smell almost knocked her over as she walked through the property.

"There's an obvious smell of death. There's a smell of feces, there're dead rabbit carcasses all over the place on the grounds outside the barns," said Gravestock.

"I lost count at about 25 to 30 dead rabbits in various stages of decay."

Called OSPCA three times

Gravestock says she was born and raised on a farm but has never smelled anything like what she experienced on the property which has a house and three barns.

She says she was told the property is a rental and went up for sale about a year ago.

"When I pulled in to look, another truck pulled in and told me that the owners had walked away from the farm and turned the rabbits loose," she said.

"I don't know if that's true. But someone opened the doors and dumped food outside."

Gravestock, who first noticed a few rabbits running loose last fall and slowly saw those numbers rise, said she called the OSPCA when the number reached 50.

At the time, the OSPCA told her there was "no law against letting your animals outside — even if they get eaten by coyotes," she said.

After her recent exploration of the property she made two more calls to the agency who did respond and posted a notice on the house door.

Alison Cross, the director of marketing and communication with the provincial office of the Ontario SPCA, told CBC News she could not speak to the details of the investigation, as it is ongoing.

"So far our investigation has revealed that the rabbits were set loose by trespassers on the property and teams from the farm have been working to gather the loose rabbits, provide them food, water and the necessary care they require," said Scott.

"Sadly some of the rabbits have died after being hit by cars or attacked by wildlife."

'It was like a horror movie'

Since Gravestock posted her video of the Holstein property, others have followed suit and found more disturbing scenes inside barns on the property.

Jenny McQueen with the group Direct Action Everywhere in Toronto said she went inside in an attempt to rescue some of the rabbits but wasn't prepared for what she found.

"I had to first climb over, like a three foot mound of rabbit feces that was crawling with maggots and flies. There were moths crawling around," said McQueen. "It was like a horror movie."

"You had to push your way through all these hanging feces-fur-cobweb things that were like two foot, hanging down. And then above you could see pee coming down and rabbits defecating on this pile."

McQueen said she took four bunnies to the vet and three had to be euthanized. Two baby bunnies are being syringe-fed in an foster home and she said her group is optimistic the two would survive.

Click through for Jenny McQueen's video of inside the farm buildings (warning: graphic content)

Carol Gravestock's video from outside the farm buildings: