A new study of over 1,300 cats has found that cats are healthier when fed vegan diets compared with cats that were fed meat-based diets, which adds more evidence to the hypothesis that domestic cats may no longer be the obligate carnivores people thought they were. The new data shows that cats fed vegan diets had better health outcomes for all the seven general health indicators studied.

The study, authored by Veterinary Professor Andrew Knight from both Winchester University, UK, and Griffith University, Australia, Dr Alexander Bauer from LMU Munich, and Dr Hazel Brown from Winchester University, is titled, “Vegan versus meat-based cat food: Guardian-reported health outcomes in 1,369 cats, after controlling for feline demographic factors”. Published in September 2023 in the scientific journal PLOS ONE, it is the largest such study published to date, covering 1,369 cats fed vegan or meat-based pet food for at least one year. 

Differences between diet groups in age, sex, neutering (desexing) status and primary location (outdoor vs. indoor) were all controlled for. The results show that, for average cats fed vegan diets, there was a risk reduction of 7% of increased veterinary visits (possibly indicating illness), 15% of medication use, 55% of progression onto a medical diet (after being fed a vegan or meat-based diet), 4% of reported veterinary assessment of being unwell, 8% of reported veterinary assessment of more severe illness, 23% of companion animal guardian opinion of more severe illness, and 16% of the number of health disorders per unwell cat. The authors state that, although none of these reductions were statistically significant by themselves, collectively they reveal a strong trend. 

Additionally, the prevalence of 22 of the most common feline health disorders was studied, resulting in 42% of cats fed meat and 37% of those fed vegan diets suffering from at least one health disorder, and 15 disorders most commonly found in cats fed meat, while only seven most commonly found in cats fed vegan diets. 

Professor Andrew Knight, the study leader who has also done extensive research on vegan diets in both dogs and cats, said, “For every single general health indicator studied, these cats had better health outcomes when fed vegan diets. This represents a strong and consistent trend. It indicates that pet food manufacturers are now designing and creating vegan pet foods to include all necessary nutrients, but with fewer of the dietary hazards that are prevalent within meat-based pet foods. Cats consuming vegan diets have better health outcomes, as a result. 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. 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.” 

In 2021, leading veterinary nutritionist Dr Sarah Dodd and colleagues published a study of 1,026 cats, of whom 187 were fed vegan diets. Cats fed vegan diets were more frequently reported by their guardians to be in very good health. They had more ideal body condition scores and were less likely to suffer from gastrointestinal and liver disorders than cats fed meat. No health disorders were more likely, for cats fed vegan diets. In a 2006 study, veterinarians Dr Lorelei Wakefield and colleagues found similarly positive results for 34 cats fed vegetarian diets (nearly all were vegan), compared to 52 cats fed meat. 

Jordi Casamitjana
“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’.