A new study estimates that if the world’s dogs and cats switched to a vegan diet, billions of animals would be saved from slaughter each year, reducing greenhouse gas emissions equivalent to those of Saudi Arabia or Australia.
Extending a strict vegan diet to all of humanity would also save calories and feed everyone on the planet.
This is because it takes 6kg of plant protein to produce 1kg of high-quality animal protein, so fewer livestock means more calories for humans and pets.
Numerous studies over the past 15 years have shown that dogs and cats can live healthy lives on a nutrient-dense plant-based diet, provided they contain the essential nutrients typically found in meat.
Researchers have now begun to quantify the environmental impact of pets’ diets and how that might change if they become vegetarians.
Professor Andrew Knight of Australia’s Griffith University estimates that this would prevent the slaughter of approximately 7 billion livestock and billions of aquatic animals.
It would also free up large tracts of land that could potentially be rewilded, allowing nature to recover and reducing pollution from animal waste, which often flows into rivers and lakes, further damaging ecosystems.
The global dog population was estimated at 471 million in 2018, with the combined weight of all canids equaling the weight of all remaining wild land mammals.
Vegan pet diets are typically made from plants, but could also be made from yeast, fungi or seaweed in the future, as some companies are using yeast, fungi or seaweed to develop meat substitutes for humans.
Professor Knight said: “This study shows that a vegan diet can be beneficial to the environment not only for humans but also for dogs and cats.
“However, to safeguard health, it is important that people only feed vegan pet foods that are labeled as nutritionally complete and produced to good standards by reputable companies.”
He also stressed that the data he used on pet numbers and animal energy requirements may have underestimated the true environmental benefits of a vegan diet, and that he had to make some assumptions, so more research is needed to make his findings more reliable.
For example, Professor Knight looked to US data when calculating the composition of the global diet, rather than calculating differences across all different countries. He also estimated environmental impacts using data from 2009 to 2011, which would give more accurate results if the data were updated.
Danny Halpin is PA environment correspondent.