A police dog that attacked an innocent man has been dropped from duty and must pass rigorous testing before working again.

Early last Friday, the German shepherd lunged at Brett Abraham, 63, while the Epsom man was chasing an intruder at his property.

A dog handler on the scene saw the offender attempt to cycle away so commanded the animal to "apprehend".

But the man swerved his bicycle and the dog attacked Mr Abraham instead.

"The dog has redirected onto Mr Abraham and that is the issue we're addressing because that is unacceptable," said Inspector Mark Hall, of the Auckland dog section.

"I can understand how it's happened but it still should not have happened," he said.

Mr Abraham said he was about 30m away from the intruder, in the opposite direction.

"He would have had to have done a complete u-turn to attack me."

He questioned why the dog came at him with a trail of lead, but Mr Hall said that was standard practice.

"If he's tracking, the handler is not going to stop the track, go forward, unclip the dog and go ... It's also a control thing because when he gets up there there's more to grab onto."

Mr Abraham suffered two wounds to the left leg - one on the upper thigh, the other the lower leg - and spent two hours in surgery at Auckland City Hospital.

Mr Abraham is back home now, but said he was in "absolute agony" and making daily trips to the doctor for dressing changes. "It feels terrible," he said. "It's 50 times worse than standing on a nail."

He planned to seek legal advice on getting compensation for the attack and was disappointed he had not received a formal apology from police.

Mr Abraham said he was still angry police had denied the dog handler left him bleeding on the driveway to attend to the intruder.

"Blood was going everywhere and I thought, 'Christ, I'm going to die here'," said Mr Abraham, who had a quadruple bypass operation just over a year ago.

Mr Hall said last week that the handler returned to his vehicle to get medical supplies before going up to the Abraham home to help treat the wounds.

He expected a decision today on whether the dog was fit for work.

The dog would be put through a number of staged scenarios and commanded to attack offenders, with different distractions in place, said Mr Hall.

"The dog will not be deployed operationally until the assessment is complete."