Cutting down the amount of meat we eat helps reduce greenhouse gas emissions associated with agriculture. But what about the meat that our pet dogs eat?

Our new study shows that feeding dogs can have a larger negative effect on the environment than the food their owners eat. For a collie or English springer spaniel-sized dog (weighing 20kg), 40% of tested dog foods have a higher climate impact than a human vegan diet, and 10% exceed emissions from a high-meat human diet.

Dog food comprises a significant part of the global food system. We have calculated that producing ingredients for dog food contributes around 0.9-1.3% of the UK’s total greenhouse gas emissions. Globally, producing enough food for all dogs could create emissions equivalent to 59-99% of those from burning jet fuel in commercial aviation.

The type of animal product used to produce pet food really matters. The environmental footprint of dog food differs for prime cuts and offal or trimmings.

Cuts like chicken breast or beef mince are used in some dog foods but are also commonly eaten by people. Selling these “prime cuts” provides around 93-98% of the money from selling an animal carcass.

By-products like offal and trimmings – which are less sought after for human consumption, much cheaper, but highly nutritious – are widely used in pet food. We assign more of an animal’s environmental footprint to high-value cuts and less to these by-products.

Greenhouse gas emissions for different types of dog foods:

Some previous studies have given by-products the same environmental impact by weight as the highest‑value cuts, directly using figures calculated for human food. This “double counts” livestock impacts and substantially overestimates the footprint of pet........

© The Conversation