Should you be feeding your dog a vegan diet?
In April 2022, scientists at the University of Winchester in the United Kingdom announced that dogs fed on a vegan diet appeared to be healthier than those on a conventional meat-based diet. However, a new study from the University of Liverpool suggests that these claims were unfounded.
Interest in vegan dog food has skyrocketed in recent years, with the global market being valued at $12.27 billion in 2021, according to analysis by Data Bridge Market Research. Proponents of plant-based pet food argue that it is more sustainable and ethical than traditional meat-based diets, which currently account for roughly 20 percent of livestock consumption in the United States.
But are these meat-free diets safe?
In the Winchester study, published in the journal PLoS ONE, 2,639 dog owners completed an online survey to investigate the relationship between their dogs' diets and their overall health. Dogs were fed either conventional meat, raw meat or vegan diets for at least one year and assessed on seven general indicators of health, including number of visits to the vet and diagnosis with common health disorders. Owners were also asked to give their subjective opinions on their dogs' health.
At the time, it was concluded that dogs fed on raw meat and vegan diets fared significantly better than those on a conventional meat-based diet. However, the new analysis by the University of Liverpool throws these conclusions under scrutiny.
"On first reading this paper in 2022, it was evident that the study exclusively relied upon owner survey data and had an observational design, meaning that the associations between diet type and dog health could only suggest a possible correlation and not causality," Alex German, professor of Small Animal Medicine at the University of Liverpool and co-author on the new study, said in a statement.
"In other words, 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.' Further, the statistical analyses used did not explore the effect of possible confounding from other variables, such as the age and breed of the dogs and owner variables including age, gender, education and diet."
The Liverpool researchers said that these variables may have skewed the owners' perception of the dogs' health in the original study. Therefore, in a new study published again in PLoS ONE, German and co-author Richard Barrett-Jolley conducted further statistical analysis to remove these confounding variables.
Owner opinions on their pets' health were most strongly associated with the age of their dog, with owner age, education and pet breed also playing a role. Once these confounding variables were added to their new statistical model, the association between subjective pet health ratings and vegan food became insignificant.
In other words, once these confounding variables were accounted for, vegan dogs did not seem to be statistically more healthy than meat-eating ones, as their owners perceived them.
"We know how seriously owners take their pet's health," Barrett-Jolley, professor of Neuropharmacology at the University of Liverpool, said in a statement. "By revisiting and further interrogating these data, we have been able to draw more nuanced insights.
"Crucially, we cannot draw a firm conclusion as to what diet type is actually best for dogs; this was never possible given the nature of the original dataset and study design. However, we can conclude that variables other than dog diet are more strongly associated with owner opinions about the health of their dog."
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