The most comprehensive peer-reviewed study so far has shown that dogs fed nutritionally sound vegan diets maintain health outcomes as well as dogs fed meat-based diets. Scientists assessed the health of 15 dogs by analysing blood cells and biochemistry, blood nutrient levels, urine, veterinary clinical parameters, and monthly dog guardians’ questionnaires. The dogs were fed solely vegan diets based on pea protein for an entire year, making it one of the longest studies of its kind so far.

The study, titled “Domestic dogs maintain clinical, nutritional, and haematological health outcomes when fed a commercial plant-based diet for a year”, and published in the leading scientific journal PLOS ONE on 16th April 2024, was authored by scientists from the Western University of Health Sciences, College of Veterinary Medicine, California, US.

The results showed that overweight or obese dogs achieved a healthier weight, whilst the remainder maintained normal weight. No clinically significant changes occurred within blood and urine. Blood levels of essential and non-essential amino acids and vitamins were all generally maintained. In a few cases, previous deficiencies following a meat-based diet either improved or disappeared, including L-taurine and L-carnitine (important for cardiac health), vitamin D (indispensable for immunity and bone health), and folate (required to produce red blood cells). Blood markers of cardiac health were assessed, with no signs of heart disease found, and in some cases, indicators of cardiac health improved (in contradiction to the suggestions that peas might contribute to heart disease in dogs).

Dr Annika Linde, the veterinarian leading the study, said, “Evolutionary adaptations have resulted in a digestive system that enables dogs to maintain health on nutritionally complete omnivorous diets, including those free of animal ingredients. Our study offers new evidence on outcomes in clinically healthy dogs who thrive without consumption of animal-derived ingredients. Notably, foods produced independent of factory farming are also more sustainable and ethical.” 

Veterinary Professor Andrew Knight has published several of the key studies in this field, including very large-scale studies showing that both dogs and cats normally achieve equivalent or superior health outcomes, when fed nutritionally-sound vegan diets. He also analysed the environmental benefits of vegan pet diets in a recent study. He stated, “If all the world’s dogs went vegan, it would save more greenhouse gases than those emitted by the UK, land larger than Mexico, and 450 million additional people could be fed with food energy savings – more than the entire EU population. With 13 studies now demonstrating good health outcomes achieved by nutritionally-sound vegan pet diets, and several others demonstrating major environmental benefits, a compelling case now exists for environmentally-friendly vegan pet diets.”

“Originally from Catalonia, but resident in the UK for several decades, Jordi is a vegan zoologist and author, who has been involved in different aspects of animal protection for many years. In addition to scientific research, he has worked mostly as an undercover investigator, animal welfare consultant, and animal protection campaigner. He has been an ethical vegan since 2002, and in 2020 he secured the legal protection of all ethical vegans in Great Britain from discrimination in a landmark employment tribunal case that was discussed all over the world. He is also the author of the book, ‘Ethical Vegan: a personal and political journey to change the world’.