Veterinary academic says switching dogs to a vegan diet means they’d live longer, need less vet visits and medication, and free up food for a human population equivalent to the EU.

Australian vet turned veterinary academic, Dr Andrew Knight, outlines the environmental and health impacts of switching dogs and cats to a vegan diet in the second episode of The Pet Nutrition Show.

Dogs and cats can happily go vegan, with a better quality and longer life, and less impact on their owner's hip pocket, according to leading veterinary academic Dr Andrew Knight.

Those claims are based on Knight's study of 2500 dogs, looking at medication usage, vet visits and assessments, and a study produced by a research group at one of Canada's leading veterinary schools. It found that dogs being fed vegan diets had an average lifespan one and a half years longer than those on conventional meat-based diets. That's equivalent to around about an extra decade of human lifespan.

"We know from the 10 studies looking at health outcomes for dogs fed vegan diets, there seem to be a couple of consistent healthcare benefits… less associated problems with gastrointestinal reactions from dietary intolerances, itchy skin and allergic reactions… less likely to suffer from being overweight or obese, have better mobility, less musculoskeletal disorders," Dr Knight told The Pet Nutrition Show.

"So they're not just living an extra decade if they had been a human being, they're also having a better quality of life as well."

Dr Knight refutes the idea that as obligate carnivores cats must eat meat; that a biologically appropriate diet for a dog is a meat-based diet, and that meat-based diets are more 'digestible'.

"That's sort of wooly logic. It's fallacious thinking," he says. "What the cats need biologically and the same for dogs and indeed for any species, is a specific set of nutrients packaged up into a formulation that's sufficiently palatable so the animals will enjoy eating it and adequately digestible. And we have studies in all three of those areas now."

Dr Knight says that switching dogs and cats to a vegan diet is not just good for their health; it will also significantly reduce their impact on the environment and increase food availability.

"If the world's dogs would transition onto nutritionally sound vegan diets, you would spare more greenhouse gases than produced by the entire United Kingdom," he said. "If you were to transition all the world's dogs onto nutritionally sound vegan diets, you would be able to feed another 450 million people with the food energy saved, and that's more people than in the entire European Union."

Knight is so concerned about the impact of human and pet food on the environment, he left full time academia to concentrate on research and advocacy.

"We're in the biggest crisis of our generation and the ones that will follow, in terms of climate change, biodiversity loss, the wholesale destruction of the other species with whom we share our planet. Since I was born in 1970, more than 50% of animal populations on the planet have disappeared. So I think we all need to be looking at what we can do to most effectively address this problem. For me, it wasn't remaining an academic."

• Dr Andrew Knight practised as a vet for over a decade, founded the University of Winchester's Centre for Animal Welfare in the UK and is currently Adjunct Professor of Animal Welfare at Griffith University.
• Knight A (2023) The relative benefits for environmental sustainability of vegan diets for dogs, cats and people. PLoS ONE 18(10):
  e0291791 The relative benefits for environmental sustainability of vegan diets for dogs, cats and people
• https://sustainablepetfood.info/
• The Pet Nutrition Show is a weekly podcast hosted by small animal nutritionist Dr Anna Sutton and Planet A Pet Food CEO Amanda Falconer, that looks at nutrition, food hacks, sustainable pet food and more, with researchers and vets from around the world.
• The episode is available on Spotify, and Apple Podcasts.