Owners should consider doing without, downsizing or even eating their pets to help save the planet, according to a new book.
It claims that the carbon footprint left by domesticated animals is out of proportion to the size of their paws.
A medium-sized dog has the same impact as a Toyota Land Cruiser driven 6,000 miles a year, while a cat is equivalent to a Volkswagen Golf.
But rabbits and chickens are eco-friendly because they provide meat for their owners while a canary or a goldfish has little effect on the environment.
At the same time a pair of hamsters do the same damage as running a plasma television, suggests the book Time to Eat the Dog: The Real Guide to Sustainable Living.
New Zealand-based authors Robert and Brenda Vale base their findings on the amount of land needed to grow food for pets ranging from budgerigars to cats and dogs.
They say an average Collie eats 164kg of meat and 95kg of cereals a year, giving it a high impact on the planet.
But a pair of rabbits can produce 36 young annually, which would provide 72kg of meat and help decrease the owner's carbon footprint.
Mr Vale, an architect who specialises in sustainable living, said: "There are no recipes in the book. We're not actually saying it is time to eat the dog.
"We're just saying that we need to think about and know the (ecological) impact of some of the things we do and that we take for granted."
He explained that sustainability issues require us to make choices which are "as difficult as eating your dog".
Mr Vale added: "Once you see where cats and dogs fit in your overall balance of things, you might decide to have the cat but not also to have the two cars and the three bathrooms and be a meat-eater yourself."