Study reports healthier outcomes for cats fed on vegan diets

A survey of cat guardians is likely to generate plenty of debate after it announced those who fed their pets vegan diets report healthier outcomes.

While the results, published in PLOS One, aren’t statistically significant, they do represent the largest study of its kind to date on cats and vegan diets. But, as they’re based on survey data, independent researchers caution against considering the results conclusive.

The study was funded by organisation Proveg International, which aims to replace 50% of animal products globally with plant-based and cultivated foods by 2040.

“This offers exciting potential to improve not only feline health, but also to address the very significant environmental impacts of the livestock sector created through pet food production,” says lead author Professor Andrew Knight, an adjunct at Griffith University, in Brisbane, Australia.

“However, to safeguard the health of our feline friends, it is important that pet guardians feed only commercial vegan pet foods labelled as nutritionally complete, produced by reputable companies with good standards.”

The researchers collected information from 1,369 cat owners in an online survey. Respondents were asked about the general health, and then the diets, of one cat living with them for at least a year.

Among the respondents, 1,242 (91%) fed their cats meat-based diets, while 127 (9%) fed them vegan diets.

After controlling for a range of factors like age and sex, the researchers examined 7 indicators of general health reported by the cat owners.

They found that vegan cats were reported as healthier on all 7 outcomes: veterinary visits; medication use; therapeutic diets; reported veterinary assessment of being unwell; reported veterinary assessment of more severe illness; the owner’s opinion of more severe illness;  and number of health disorders per unwell cat.

None of the reductions were statistically significant, meaning it’s possible these reductions happened by chance, although the researchers say the trends are still “clear and consistent”.

“As our environment and food ability changes, it is important to investigate alternative options for ourselves and our animals. Currently there is limited information on the safety of alternative diets for cats, who struggle to meet their nutritional needs without a high percentage of meat in their diet,” says Julia Henning, a PhD candidate at the University of Adelaide, who wasn’t involved in the research.

“Without adequate supplementation of nutrients such as taurine, cats may suffer from serious health conditions such as liver and heart problems.

“Cat studies are prone to methodology issues due to a cat’s ability to come and go as they please. It is likely that some of the ‘vegan’ cats included in this study may actually be supplementing their diet outside the home,” Henning adds.

Knight says that the researchers controlled for this by including primary location (outdoor versus indoor cat) in their regression models.

“The study relied on surveys, which are subjective and can be prone to bias,” points out Dr Alex Whittaker, a senior lecturer in animal welfare and law at the University of Adelaide’s School of Animal and Veterinary Sciences, who also was not involved with the research.

“Additionally, the duration of time the cats had been on these diets remains unclear, and it is known that deficiencies do take several months to develop. In an ideal world, scientists would conduct clinical trials involving a large cat population, directly measuring health through veterinary exams and lab tests.

“Nevertheless, this study adds to a growing body of evidence suggesting that vegan diets for cats might not be as harmful as once believed. It challenges conventional wisdom and prompts further research into the matter,” says Whittaker.

In their paper, the researchers acknowledge that – being survey-based – their results could be prone to participant bias.

“Large-scale cross-sectional or ideally, longitudinal studies of cats maintained on different diets, utilising objective data, such as results of veterinary clinical examinations and laboratory data, as well as veterinary medical histories, should yield results of greater reliability,” they write in their paper.

Knight tells Cosmos that such studies are very difficult to fund.

“Because of their cost, when they do occur, only small numbers of animals are normally included, which limits their statistical validity, and their generalisability to the wider cat population,” he says.

“I would caution that just as you would not base your own diet on a survey of other people, it’s best not to base your cat’s diet on the results of this survey. As always, it’s best to consult a veterinarian if you are concerned about your cat’s diet,” says Henning.

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