A number of Canadian police agencies are changing their policies on stun-gun use in light of a new training bulletin from the manufacturer of the weapon.

Taser International says the guns should not be aimed at a suspect's chest whenever possible. Instead, officers are advised to target the abdomen, legs or back.

"Note, we have lowered the recommended point of aim from centre of mass to lower centre of mass for front shots," the company says in the bulletin on its website.

"When possible, avoiding chest shots with electronic control devices avoids the controversy about whether ECDs [electronic control devices] do or do not affect the human heart," said the bulletin said.

'The RCMP is immediately directing members to, where practical, avoid intentionally targeting the chest, the head and pre-existing injury areas, if known.'—Sgt. Greg Cox, RCMP spokesman in Ottawa

Police forces in Vancouver, Calgary and Winnipeg say they will be following the new avoid-the-heart directive.

Winnipeg city Coun. Gord Steeves, who heads a committee overseeing the Winnipeg Police Service, says the department will follow Taser International's recommendations for both safety and legal reasons.

"You'd be wise to follow that, firstly of course from a safety perspective, and secondly from a liability perspective. You better work that into your policy, if the company who makes the product is actually saying that," he told CBC News.

But he added this caveat: "There are sometimes struggles. A perfect shot is not always possible in every circumstance."

The RCMP is also implementing the directive.

The force's stun gun policy is already under scrutiny at an inquiry looking into the case of Polish immigrant Robert Dziekanski, who died after being shocked by officers with a Taser in the arrivals lounge of Vancouver International Airport two years ago.

"The RCMP is immediately directing members to, where practical, avoid intentionally targeting the chest, the head and pre-existing injury areas, if known," said Sgt. Greg Cox, an RCMP spokesman in Ottawa.

Taser International says the risk of a cardiac arrest in connection with Taser use is low, but if this were to happen after the weapon hits the chest area, it would place police and the company in the "difficult situation of trying to ascertain what role, if any, the Taser ECD could have played in a unique situation that cannot be replicated in human clinical safety evaluations."