Tutty says most people laughed off errors but some were annoyed when dogs were recorded wrongly as un-neutered because the owners had to produce a certificate or a vet's letter to prove otherwise.
Another dog owner, Gillian, who declines to give her surname, adds: "It's a waste of time. I know it's easy enough to tell that my dog doesn't have any balls. But to go to all that effort, and then you've got to go to the council, it's a bloody pain."
Dog owner Shelly Maxwell wrote on Facebook: "Yep, had ours fixed and new rego shows she has her bits back. They were given paperwork last year, stupid council."
The council's Nigel King says most of the 112,000 registration forms were trouble-free. In some cases, vets hadn't updated details.
"It's hard to determine whether it's an error on our part. We're not getting hundreds [of forms] back."
Karen Laurie says council staff at Glen Eden apologised when told of the mistake. Even a council employee received an incorrect form.
"I think someone was just keying in the information and just didn't take any notice of what they were doing."