Two animal rights groups are set to appear in court Thursday in an effort to stop Ontario's animal welfare organization from destroying 21 dogs seized during a raid on an alleged dogfighting ring.

Dog Tales Rescue and Sanctuary and Animal Justice have filed applications to intervene in the case, both arguing the dogs -- all pit bulls -- deserve a proper defence.

In January, the Ontario Society for the Prevention of Cruelty to Animals filed an application in a court in Chatham, Ont., to euthanize 31 dogs seized during the raids.

The OSPCA, which requires court approval to destroy animals for behavioural reasons, says an evaluation of the animals concluded that 21 of them are a menace to society and cannot be rehabilitated.

In documents filed with the court, Animal Justice says it has "credible evidence" that the behavioural assessments done on the dogs, which are the foundation of the Crown's case, are scientifically unreliable and do not show that the dogs should be killed.

Dog Tales Rescue and Sanctuary, located in King City, Ont., also questions the "quality and accuracy" of the assessments and claims in court documents that it has expertise in the rehabilitation of dogs.

John Nunziata, a lawyer representing Dog Tales, says his client is offering to cover all costs associated with the case and has experts in Florida willing to rehabilitate the dogs.

Ken Marley, the lawyer who represents the dogs' owners, said his clients welcome intervention by both Animal Justice and Dog Tales.

"Those interveners will be opposed to the destruction of the dogs, which is our position as well," Marley said.

"Certainly having the expertise and resources of those organizations as well as additional voices in the courtroom opposing destruction of the dogs is important."

The owners -- John Robert, Kim Thu Thi Robert and Michel Conrad Gagnon -- have agreed in principle to transfer ownership of the animals to Dog Tales.

Those three, plus two others, face more than 300 animal cruelty and weapons-related charges. The criminal case has been severed from the euthanization application and remains in the early stages with a trial a long way off.

The Crown is opposed to the groups' intervention attempts, according to court documents, and says "there is no authority in this court" to allow the animal rights groups to intervene.

Jennifer Bluhm, the deputy chief of the OSPCA, says the 21 dogs continue to show signs of aggressive behaviour, but seven other dogs that aren't part of the euthanasia application are improving during rehabilitation. Three of the seized dogs have been put down for medical reasons.

"We have a responsibility to keep the public safe," Bluhm said. "These dogs are bred to fight and trained to kill."