Nutritionally-sound vegan diets are the healthiest and least hazardous choices for owners to feed their pet dogs, according to the authors of a new research study.
The study of 2,639 dogs and their owners, led by the University of Winchester, is among the first large-scale studies to explore how health outcomes vary between dogs fed meat-based or vegan diets.
For the research, dog owners provided information about one dog which was fed either a conventional meat, raw meat or vegan diet for at least one year.
The researchers looked at seven general indicators of ill health in dogs - including unusually high numbers of visits to the vet; whether the dog took medication; and the percentage of unwell dogs - and 22 of the most common canine health disorders. Dog owners were asked to report their own opinion of their dog's health and also what they believed their vet's assessment to be.
The findings show that, considering all seven general indicators of health, dogs fed conventional meat diets appeared to be less healthy than those fed either a raw meat or a vegan diet. They had poorer health indicators in almost all cases.
Dogs fed raw meat diets appeared to fare marginally better than those fed vegan diets. However, the effect sizes were statistically small, in every case. Additionally, the dogs fed raw meat were significantly younger on average, which has been shown to have protective effects, improving health outcomes.
Additionally, factors unrelated to health may have improved apparent outcomes for dogs fed raw meat, with the proportion of dogs who had not seen a vet in the last year markedly higher in this group.
If ages were equalised and non-health related barriers to visiting the vet were accounted for, the researchers say it is not possible to conclude that dogs fed raw meat diets would be likely to have health outcomes superior to those fed vegan diets.
The researchers also looked at the prevalence of 22 specific health disorders, based on predictions by vet assessments. Health disorders included problems with their skin/coat, dental issues, allergic dermatitis and arthritis - the most common disorders experienced by dogs. Percentages of dogs in each dietary group considered to have suffered from health disorders were 49 per cent for conventional meat diets, 43 per cent for raw meat diets and 36 per cent for vegan diets.
Additionally, previous research indicates that raw meat diets are often associated with dietary risks, particularly pathogens such as bacteria and parasites, which are more common in such dogs, as well as their guardians - indicating concurrent risks to humans sharing their households with such dogs.
Andrew Knight, Professor of Animal Welfare and Ethics and Founding Director of the Centre for Animal Welfare at the University of Winchester, said: "Pooled evidence to date from our study and others in this field indicates that the healthiest and least harmful dietary choice for dogs among conventional, raw meat and vegan diets, is a nutritionally-sound vegan diet.
"Vegan diets are among a range of alternative diets being developed to address increasing concerns of consumers about traditional meat-based pet foods, including their environmental 'pawprint', their perceived lack of 'naturalness', health concerns, or impacts on those animals in the food chain used to formulate such diets.
"Regardless of ingredients used, diets should always be formulated to be nutritionally complete and balanced, without which adverse health effects may eventually be expected to occur," he added.
"Among the dog owners taking part in the study, the health of their pet was one of the most important considerations in choosing a diet," said Dr Hazel Brown, co-author of the study at the University of Winchester.
"Alternative diets and pet foods offer benefits to both environmental sustainability and the welfare of farmed animals which are processed into pet foods, but many pet owners worry that they may harm the welfare of pets. There is no evidence that biological and practical challenges in formulating nutritionally adequate canine vegan diets mean their use should not be recommended."
The study Vegan versus meat-based dog food: guardian-reported indicators of health is published in PLOS ONE and is available online at this link.
The authors are: Professor Andrew Knight, Centre for Animal Welfare, University of Winchester; Dr Hazel Brown, Faculty of Health and Wellbeing, University of Winchester; Eason Huang, an independent consultant, based in Brisbane, Australia, and Nicholas Rai, Menzies Health Institute Queensland, Griffith University, Australia.
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