A Montreal woman is suing her osteopath for more than $800,000 after her arm had to be amputated following a treatment.

Danielle Rousseau, 55, says she had been visiting Pierre Coallier, in St-Bruno, Que. for three years, returning to him regularly after developing a neck strain in the summer of 2010.

The holistic medical practitioner performed a treatment to try to relieve pain in her shoulder. But a day after the treatment, Rousseau contends she knew something was very wrong.

"A day after, my hand was paralyzed and it was hurting a lot," Rousseau tells CTV Montreal.

She went back to her osteopath, who allegedly told her to relax, saying that her pain was stress-related. She went home to rest. But when she woke up the next morning, her arm was in worse condition.

"My hand was already grey, there was no circulation," she says.

Rousseau was rushed to hospital where doctors discovered a blood clot in her shoulder.

But by then, it was too late. The circulation to her arm had been cut off for too long and her arm had to be amputated.

Now she's suing because she says the amputation could have been prevented if her osteopath had told her to seek urgent medical help.

Her lawyer, Jean-Pierre Menard, has helped her file an $800,000 lawsuit against the osteopath.

"We feel he didn't respect the limits of his expertise," Menard says. "He should have sent her straight to hospital."

None of Rousseau's allegations have been proven in court.

In Quebec, the only people who are allowed to establish a diagnosis are medical doctors.

Pierre Coallier, who still practises, is not a member of the osteopath association of Quebec, called Registre des Ostéopathes du Québec. Membership in the 900-member group is not mandatory.

Benoit Yergeau, the head of the registry, says more oversight of the profession is needed.

"We've been asking the government to regulate the profession, and to set a minimal level of education which would be the norm, or the standard," he says.

Coallier didn't respond to interview requests from CTV Montreal. But Rousseau says she can't wait to face him in court.

With a report from CTV Montreal's Stephane Giroux