But the officer in question told an internal review he saw the "hairs on the dog's back begin to rise" before he fired the capsicum spray and claimed the chemicals "seemed to have no effect on the dog".

The incident - which was captured on CCTV and revealed by The Canberra Times - occurred as police conducted a search on Justen Storay's unoccupied Griffith home in May.

Documents obtained under freedom of information reveal the officer was found to have "seriously breached" the AFP Code of Conduct by using "excessive force" on the chained dog, although his misconduct was downgraded to a category two offence.

But the review concluded the officers' action were "necessary and proportionate to prevent the dog from continually charging and possibly breaking free and biting" and the dog – known as Laps – sustained no visible injuries despite Mr Storay's complaints.

Despite CCTV vision showing three officers apparently laughing with one allegedly recording the event on his mobile phone and another seen barking at the dog, the review said no members saw the officer fire capsicum spray at the dog.

"None of the members saw or were present when [redacted] deployed OC spray. No one smelt the OC spray in the air, saw the dog in pain, injured or in any distress," read the review.

"Member who were close to the dog shortly after the OC spray was deployed did not see the dog produce copious amounts of mucus, paw at its face, or show any signs of distress or pain, as would normally occur from exposure to OC spray."

But when Mr Storay returned to his home, he alleged the dog suffered red, watery eyes and was visibly upset but did not require veterinary treatment.

Mr Storay said his dog's injuries had been overwhelming psychological and the dog – which he trusted to play with his children aged eight and three - had "cowered", been "stand-offish", and seemed "really shocked" after the incident.

The officer, whose name is redacted in the documents, said the dog began to bark as he approached the garage door before he used his capsicum spray.

"As I got within two metres of the door, the dog charged at me," he said.

"At this time I retreated from the door, the dog continued to run at me and lunged in an effort to attack me. At this point I discharged my OC spray in the direction of the dog."

The officer alleged the dog continued to remain aggressive and barked and growled at police, despite the review concluding the dog was calm and wagging its tail some moments after the incident.

The review stated "all members felt varying levels of apprehension towards the dog" although also stated the dog became comfortable with some officers and enjoyed being patted.

The team leader of the search said the dog was initially aggressive on arrival but became used to the presence of police and "reduced its aggressiveness towards me and other members."

"At some stage whilst conducting the search of the premises, I approached the dog and held out my hand," said the team leader.

"The dog approached and sniffed my hand, then allowed me to pat him. I patted the dog for a considerable period of time."

Another officer described the dog as being "slightly timid and a bit curious" and said it watched officers attentively with ears slightly raised.

"I held my hand out to him and he came and sniffed it. I patted him on the head and spoke to him," he said.

"He appeared calm and curious about the people around, and was very observant when anyone came into the backyard, watching people around him."

When the footage emerged, ACT Policing shifted the male officer into a desk job and launched internal investigation through AFP Professional Standards.

In a press release, Assistant Commissioner Rudi Lammers said the complaint had been the subject of an extensive investigation by professional standards, which confirmed a breach.

But he said no criminal charges would be laid against the officer because there had been no evidence the dog had been injured by the spray. Instead, he was ordered to undergo formal counselling and retraining.