Staff and other volunteers rushed to help Paula, who was bleeding heavily from her wounds. The dog eventually let go and staff were able to secured it.
"Luckily, a lot of staff are trained in first aid. She was transferred to Middlemore (Hospital) and because they were open wounds she went to theatre the following day. She is now at home recovering."
Ms Kalin said: "First and foremost, SPCA Auckland sincerely regret this occurred ... Certainly for us, it's just not what we would want to happen to any staff or volunteer, but I guess with all animals there is an element of risk."
SPCA was now reviewing its procedures around dogs, although it may never be known what set the dog off.
The peer review is under way now, although Ms Kalin was confident it was a rare occurrence. She'd been told that in the past 30 years there had only been two other incidents at the SPCA where dog bites required more treatment than just first aid.
"So that shows you how rare it is."
Immediately after the attack volunteers were removed from working with adult dogs, but that is being gradually reinstated.
Ms Kalin had visited Paula in hospital.
"One of things she said to me was 'I hope I can come back to the SPCA."
The dog had been given to the SPCA on October 29 because its owner had to care for a sick relative. It was considered a "family dog".
"It had been vet checked, continually assessed by staff through its stay, and was de-sexed. Some would say certain breeds will be higher risk but this was a family dog that we had no hint at all of this dog having issues."
The dog was euthanised because public safety was paramount.
A spokesman for the Ministry of Business, Innovation and Employment said they were aware of the incident and were investigating.