Campaigners against drug sniffer dogs say a death from a suspected overdose at Perth's Big Day Out music festival on Sunday shows the police tactic is dangerous.

Friends of 17-year-old Gemma Thoms told police she took three ecstasy pills at once because she was scared she would be caught by the dogs.

She collapsed, was taken to a first aid tent and later died in hospital.

New South Wales Greens MP Sylvia Hale has been warning governments for years this might happen if they use sniffer dogs at festivals.

"It just makes one incredibly sad," she said.

"What do you say to the parents?

"What do you say to the police or the state governments who have so consistently ignored the warnings?"

Ms Hale says a 1996 report by the NSW Ombudsman criticised the use of dogs at music festivals, saying they are ineffective.

"They're real PR exercises, trying to persuade the public at large what they're doing is effective. Whereas, indeed, it really is life-threatening behaviour," she said.

But WA Police are making no apologies for the sniffer dog operation at Sunday's Big Day Out, saying it was part of a harm minimisation attitude.

Premier Colin Barnett has also defended police actions.

"I don't apologise for that," he said.

"As tragic as this case is, it is sadly one further example of the devastating effects of drug usage.

"To young people in Western Australian I simply say, look what's happening around [you]. Look at the tragedy, the loss of life, people with mental health problems, inability to complete school, to study, to succeed in life and in their careers."

An autopsy is yet to be conducted to confirm the exact cause of Thomas's death.