Police said about 6,800 mink were let out of four sheds at RBR Fur Farms Inc. near the Town of St. Marys after a perimeter fence was cut open overnight Tuesday.
Rancher Kirk Rankin said other farmers from the seven facilities in Perth County that rear the tiny carnivores for their glossy fur are "wound up" because it is the second break-in since late May.
Rankin said many mink were recovered on Wednesday and Thursday, including several dead ones, but he won't know the numbers until he gets the animals back into pens.
"My family has been raising these mink for almost 80 years, we like the animal," he said.
"But these other people, if they don't like fur coats, that's fine, they don't have to buy a fur coat, they don't have to wear any fur, but they sure as hell don't have the right to come into our property and do the damage that they did."
The Animal Liberation Front took responsibility for an earlier incident at the neighbouring Glenwood Fur Farm that involved the release of about 1,600 mink.
Will Hazlitt, a press officer with group, said he suspects activists who wanted to make a case against the fur industry through "economic sabotage" were responsible for this week's break-in.
"Without having a claim of responsibility, I would imagine that this is something that the Animal Liberation Front would have undertaken, just as they did at the other fur farm," he said.
He said people usually anonymously claim responsibility to criminal actions by sending the organization an email, like after the first mink farm break-in, and it will be posted online.
Gary Hazlewood, the executive director of Canada Mink Breeders, said it's the first time he's seen two break-ins within the same year, let alone two in the same area.
In early June, Hazlewood's organization offered a $75,000 reward for information leading to the arrest of the people responsible.
Hazlewood said that reward will likely be reinstated, and he is encouraging farmers to ramp up security. He said the break-ins are both costly and harmful to the animals' welfare.
"I still find it strange that people who think that they are helping animals actually put them at greater risk and don't seem to care about that," he said.
"These are juvenile animals, they're maybe 10 or 12 weeks old...they wouldn't have a clue as to what to do once they're released. They would have no ability to fend for themselves at all, at this stage. It's a high-risk thing."
Hazlitt disagreed, calling the information from Canada Mink Breeders "propaganda."
"(Mink) can absolutely survive in the wild, very similar to, for instance, orcas that have been released from captivity. They are very able, immediately almost, to adapt," he said.
"The mortality rate at a fur farm is 100 per cent."
Ontario Provincial Police Const. Kees Wijnands said investigators don't know who is responsible but that there are similarities between the two break-ins.
Police are asking anyone with information to come forward.