A new scientific review has found nutritionally sound vegan dog food, vegan cat food and vegetarian pet diets are generally well digested and broadly comparable to conventional meat-based diets.

The review, published in the journal Animals, examined 31 existing studies assessing the digestibility of vegan, vegetarian and plant-based pet diets and ingredients in dogs and cats.

Twenty-two studies focused on dogs, two on cats and seven included both species.

Digestibility was an important measure because it indicated how effectively animals could absorb and use nutrients from food.

While modern commercial plant-based pet foods were generally formulated to provide all essential nutrients, poor digestibility could still reduce nutrient absorption.

Author Professor Andrew Knight, a Professor of Animal Welfare affiliated with Griffith University’s School of Environment and Science, said the findings challenged a common perception that dogs and cats could not effectively digest plant-based proteins.

"Current evidence indicates nutritionally sound vegan and vegetarian pet diets, and their main protein sources, are generally well digested by dogs and cats," Professor Knight said.

The studies included in the review examined a wide range of ingredients used in vegan and plant-based pet food including wheat gluten, rice protein, soy-derived ingredients, peas, lentils, chickpeas, potato protein, quinoa and proteins produced through microbial fermentation.

Some studies also assessed commercially available vegan dog foods containing ingredients such as peas, barley, oats, sunflower oil and lentils.

The review found digestibility remained high overall even in studies where limited plant-based nutrients were less digestible than animal-derived ingredients.

Professor Knight said the findings should reassure owners considering nutritionally sound vegan diets for their pets.

"These findings support the use of carefully formulated vegan and vegetarian diets and challenge the notion that such diets are less digestible than conventional meat-based diets,” he said.

"I recommend pet carers check product labels.

“There should be a clear statement that the diet is nutritionally complete.

“It should come from a good pet food company that can provide information about the steps taken to ensure nutritional soundness, such as working with veterinary nutrition specialists."

Professor Knight said further research was needed to better understand the digestibility of vegan and vegetarian diets for cats in real-world settings, as well as for kittens, senior animals and pets with health conditions.

The study ‘The Digestibility of Vegan and Vegetarian Diets for Dogs and Cats’ has been published in MDPI journal Animals.