The Royal New Zealand Society for the Protection and Care of Animals says it is not negotiable to leave animals in cars during the heat of summer.
The RSPCA says animals can succumb to heatstroke in just 15 minutes because the interior of a car left in the sun can quickly reach high temperatures.
The Society's chief executive, Robyn Kippenberger, says dogs may survive but be left with permanent brain damage.
The society's chief executive, Robyn Kippenberger, says dogs may survive but be left with permanent brain damage.
"Unless you're in deep, deep shade - the sun moves and as soon as the car moves onto any part of the car, then the car heats up.
"People with the best will in the world leave their animal with some water and windows partly wound down and still that car can heat up to temperatures that animals simply can't survive at."
Veterinarians says heat stroke can be devastating, leaving a dog with organ damage or prone to epilepsy.
AA call outs for children locked in cars
The Automobile Association says it is called to about 70 incidents a month where children have locked themselves in cars and cannot open the doors.
The AA says preoccupied parents lock keys in the car, or give them to children to play with, who then inadvertently lock themselves in.
It says during warm weather, the interior temperature of a vehicle can rise very quickly and leaving children in cars can be a recipe for tragedy.
Road Service Manager John Healey says the AA will respond to calls for help by non-members, and if its staff cannot attend quickly, emergency services will be called in.
He says the locking systems of modern vehicles can take some time to disable, and windows might need to be smashed as a last resort to gain access.