Modern vegan and vegetarian diets formulated for dogs and cats show high nutritional digestibility that is broadly comparable to conventional meat-based pet foods, according to a peer-reviewed review published in May 2026 in the journal Animals. The study, authored by Andrew Knight of Murdoch University, Griffith University, the University of Winchester, and the Sustainable Pet Food Foundation, analyzed 31 distinct studies to evaluate long-standing concerns that pets descended from carnivores (dogs), or who remain biologically carnivorous (cats) cannot effectively process plant-based proteins.
Digestibility Metrics Across Plant-Based Pet Diets
According to the review published by Andrew Knight, apparent total tract digestibility (ATTD) values for plant-based pet diets consistently exceeded 80% for dry matter, 85% for organic matter, 80% for crude protein, 89% for fat, 88% for nitrogen-free extract, and 86% for energy across the five studies that measured these specific metrics. The analysis incorporated 31 studies total, with 22 focusing specifically on dogs, two focusing on cats, and seven examining both species. These investigations covered a wide array of study designs, animal populations, dietary ingredients, and processing techniques.
The findings indicate that individual vegan protein sources—including ingredients derived from legumes such as soy, pulses, grains, and microbial fermentation—are effectively digested by dogs and cats. While individual studies sometimes noted variations where specific plant proteins showed lower digestibility for particular nutrients compared to animal-based alternatives, overall dietary digestibility remained high across the board.
Addressing Carnivore Physiology and Nutritional Safety
Pet owners and carers have frequently questioned whether dogs, and particularly cats, can safely maintain health on plant-based diets given their evolutionary biology. The review addresses these physiological doubts by compiling empirical data showing that modern manufacturing and formulation techniques allow companion animals to break down and utilize plant-derived nutrients effectively. Andrew Knight noted in the study that while digestibility is a key determinant of nutritional soundness, plant-based formulations must still be carefully designed and manufactured to be nutritionally sound.
The growing consumer interest driving these dietary shifts stems from multiple factors, including concerns regarding the environmental sustainability of livestock production, farmed animal welfare, and specific pet health considerations. The 2026 review concludes that properly formulated vegetarian and vegan diets do not suffer from a fundamental lack of digestibility when compared against traditional meat-based options.
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