From Sunday, animals are allowed on trains at off-peak times as part of an Auckland Transport trial.
But pet owners will be kept on a tight leash, with strict rules in force.
They'll only be allowed on trains, and only at off-peak times - between 9am and 3pm, and from 6:30pm on weekdays, and all-day on weekends and public holidays.
They'll also have to be caged, and small enough to fit under the seat or on your lap.
Auckland Councillor Cathy Casey says pet owners need to be trusted.
"As a responsible dog owner, I'll make sure that my dog doesn't do poos and wees on public transport. If a person has an allergy and insists, 'I don't want your dog near me,' that's fine too."
If your pet does have an accident, it's your responsibility to clean it up. And if the train is crowded, don't be surprised if you're denied entry.
The trial ends in September. If successful, it may become a permanent reality. Casey expects it will be a "howling" success, saying it will bring many benefits.
"Not everybody lives anywhere near a dog exercise area or a beach... so I can see this taking a huge number of cars off the road."
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"There are many Aucklanders that may not have access to a vehicle to take their pet to the vet or for when they want to explore the city, this will potentially benefit both the owners and the pets," added Stacey van der Putten, Auckland Transport group manager of metro services.
And don't worry about getting your pooch an AT HOP card - pets travel for free.
The trial doesn't include buses, which will still be limited to disability assist dogs.