Robert and Brenda Vale, two architects who specialise in sustainable living at Victoria University of Wellington, New Zealand, have given a new meaning to the term "pet food" in their new book, "Time to Eat the Dog".

The book compares the ecological footprints of popular pets with those of various other lifestyle choices. New Scientist have added to the debate with research from John Barrett at the Stockholm Environment Institute in York, Englend and David Mackay, the UK government’s energy adviser.

So what are the results?

  • According to the Vales, a medium size dog has a larger eco-footprint than a large SUV (specifically, a 4.6 litre Land Cruiser driven for 10,000 kilometres a year),
  • A cat has an eco-footprint which is slightly less than a Volkswagen Golf.
  • Two hamsters equate to one plasma TV.
  • But you can have four canaries for one plasa TV
  • And a goldfish has an eco-footnprint (or should that finprint?) equilavent to two mobile phones.

The land required to feed the pet cat population of the top ten cat-owning countries is about one and a half times the area of New Zealand. And the land needed to feed the dogs in the top ten dog-owning countries is five times the area of New Zealand.

To put all this into perspective, the eco-footprint of a British human is about fifty times that of a cat.

We wouldn’t dare suggest what you should conclude from this but this is the Vale’s advice:

  • If you have a dog, feed it the same kind of food that you eat rather than meat-rich dog food;
  • If you have a cat, feed it on fish heads and other leftovers that you can get from a fishmonger;
  • And if you are chosing a pet "Rabbits are good, provided you eat them."