The Christchurch City Council has apologised to dog owners who were told they had to keep their menacing dogs muzzled at all times.

Owners of dog breeds classified menacing were sent a letter from the council's Animal Management Team last week notifying them the dogs must be muzzled even when inside their homes or in the property.

The council apologised on Monday saying further legal advice they received meant menacing dog breeds did not need to be muzzled even within the home or secured in the property.

"The members of our Animal Management Team are all passionate animal lovers. They were trying to prevent other animals and people from coming to harm by ensuring that the owners of menacing dogs were aware of what their obligations were," compliance general manager Leonie Rae says.

The Animal Management Team acted on the basis of a legal interpretation of what it means for a dog to be "at large" but a review of that interpretation found it was unlikely to uphold in court, Ms Rae said.

"We will be writing to the dog owners with dangerous or menacing dog classifications to update them. This will give clarity around where and when menacing dogs need to be muzzled.

"We're sorry for any confusion and upset that we have caused."

Dogs are classified as menacing either because they are a specific breed or type or because they have attacked or behaved aggressively.

The letter sent out by the Animal Management Team was prompted by 234 dog attacks in one-year, leading the council to reconsider the Dog Control Act.

Breeds that are classified as menacing include: Brazilian Fila, Dog Argentino, Japanese Tosa, American Pit Bull and Perro de Presa Canario.

- NZ Newswire