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But bystanders and police involved in the incident agreed the dog was just doing its duty.
The incident unfolded about 10am in Princes St by The Oval sports ground, when a man walking a dog had a seizure and fell to the ground.
Witness Rowallen O’Connor said another man stopped to help, before receiving a small bite from the dog.
"It was just a wee nip ... I think it was more do to with protecting its owner."
St John arrived to transport the man, who was understood to be in a stable condition, Constable Jonathan Chatfield said the incident would not be recorded as a dog bite and all on scene agreed the dog was just protecting its walker.
Dunedin City Council compliance, animal and parking services team leader Peter Hanlin said animal control officers attended.
They established the dog belonged to a relative of the man who had the medical event, and it was returned home to its owners.