"People often forget that dogs evolved from wolves and retain a number of their behaviours. While your dog might be obedient and friendly, they can - and will - bite as a defence, as a fear reaction, or simply because something is annoying them."
Mr Thompson said dogs often became aggressive when they were tied up for long periods of time, not exercised, not fed enough, not given vet treatment, not neutered or not loved. It was uncommon for a dog to attack for no reason and the cause usually related to what owners did or did not do.
Training for dogs and owners could prevent attacks. Basic commands were only part of the training. Dogs needed to learn their place in a family. "If the dog does not know its place it may bite to show that it thinks it deserves to be higher up the ladder," Mr Thompson said.
He said attacks on family members were often not reported to authorities.
"Any dog attack can have a long lasting impact on the victim and their family. To prevent this, we recommend every dog and dog owner gets training, which will greatly improve the chances of everyone in their community staying safe and happy."
Whangarei SPCA general manager Francine Shields said it was an owner's responsibility to make sure their dog was socialised from an early age.
People should also be careful about how they approached dogs, she said. They shouldn't approach a dog directly, make direct eye contact, surprise them or reach over their head. If they wanted to touch a dog they should put their palm upwards underneath the dog's chest or chin after asking the owner's permission.
"How you approach will denote how the dog responds to you," she said.
Ms Shields, also a dog trainer with the Whangarei Dog Training Association, recommended dog training for all owners. Training included dog socialisation and learning to read your dog.