On 15th May 2024, scientists from Liverpool University published a study which, it has been claimed, disputes the benefits of vegan diets for dogs reported in a 2022 study, but the professor from Winchester University leading the original study disagrees, claiming the new research using the same data set actually supports his main conclusions

The new study, published in the leading scientific journal PLoS ONE, reanalysed data used within a key 2022 study of 2,536 dogs — the largest published study within this field. That study concluded that the healthiest and least hazardous diets for dogs were nutritionally-sound vegan diets. However, guardian opinions of health were included, which may not always be reliable. For example, guardians committed to feeding vegan or meat-based diets might sometimes fail to recognise or report subsequent health problems.

The new research focused specifically on subjective dog guardian opinions of health, in contrast to the original study which examined seven general indicators of illness, including more objective data such as the prevalence of medication use, therapeutic diet use, and the frequency of veterinary visits. The original study also analysed the reported assessments of veterinarians concerning dog health, as well as the prevalence of 22 of the most common health disorders in dogs. It also considered prior studies documenting hazards (pathogens and nutritional imbalances) associated with raw meat diets.

In the new study, after conducting further statistical analysis (including machine learning), the researchers concluded that guardian opinions of health were minimally affected when vegan diets were fed. However, Prof. Andrew Knight, the leading author of the original study, told Vegan FTA that the authors of the new study published a press release stating the following about his original research: “It was not accurate to conclude that ‘Nutritionally-sound vegan diets are the healthiest and least hazardous choices for owners to feed their pet dogs.’”

Prof. Knight said he was surprised about the press release because, after having reviewed the new study, he thought that the results confirmed his original conclusions. He said, “I was relieved to see confirmation that feeding vegan diets had minimal impact on owner opinions about health. This increases my confidence in the reliability of the owner opinions we analysed.”

There have now been many studies concluding that dogs can thrive on plant-based diets (although any of these diets must be nutritionally sound). By May 2024, there were 10 studies in dogs, and three in cats, demonstrating equivalent or superior health outcomes when vegan diets are used, as well as one systematic review covering both species. In April 2024, the longest and most comprehensive peer-reviewed study demonstrated that dogs fed nutritionally-sound vegan diets maintain health outcomes as well as those fed meat. The study comprehensively analysed blood cells and biochemistry, blood nutrient levels, urine, veterinary clinical parameters, and monthly dog guardian questionnaires. It studied 15 dogs fed solely vegan diets for an entire year. Another 2022 study demonstrated that 1,000+ dogs fed vegan diets lived 1.5 years longer, on average, than dogs fed meat. 

“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’.