The review found no conclusive evidence of adverse effects from feeding pets a vegan diet, and there were indications of some health benefits. However, the overall evidence was rated as low to very low in certainty, highlighting the complexity and variability in study designs and outcomes. This suggests that while vegan diets can be safe, the decision to switch should be approached with careful consideration of the animal’s nutritional needs.

Brain Function and Behavior: Nineteen genomic regions linked to brain function were identified, with eight involved in nervous system development—these may explain the behavioural adaptability of domestic dogs compared to their wild ancestors. Dietary Adaptations: The study also found signals of selection in ten genes associated with starch digestion and fat metabolism, suggesting that early dogs evolved to digest starch more efficiently than wolves. This adaptation was crucial as it allowed dogs to thrive on a diet different from the strictly carnivorous one of their wolf ancestors.

General Health and Well-being: Most guardians reported no negative impact on their dogs’ appetite or body weight, suggesting that the vegan food was palatable and satisfying. Statistically Significant Improvements: Improvements were noted in several areas, all statistically significant: Increased activity levels and better fecal consistency. Reduced frequency of defecation, less frequent and less smelly flatus. Enhanced coat glossiness and reduced dandruff. Decreased skin redness and itchiness. Lowered anxiety levels in dogs.

Health and Wellbeing Comparisons: Owners of dogs on plant-based diets reported fewer instances of ocular, gastrointestinal, and liver disorders compared to those feeding meat-based diets. These dogs were also perceived to have greater longevity, indicating potential long-term health benefits of plant-based diets. Interestingly, owners who chose plant-based diets for their dogs tended to consult veterinarians less frequently for nutrition advice.

Nutritional Standards and Testing: Plant-based dog diets are typically formulated to meet AAFCO nutrient recommendations, similar to meat-based diets, although actual feeding trials are rare in the industry. The critique often directed at plant-based dog food regarding untested nutritional claims is also applicable to many meat-based diets sold commercially, which frequently rely solely on nutrient profile formulations without feeding trial verification. Additional tests such as dietary nutrient analysis and digestibility can further substantiate the nutritional claims of these diets, though such information is seldom disclosed on product packaging or promotional materials.

General Health: Both dogs and cats appeared generally healthy; no significant health issues directly related to the vegan diet were observed. Blood Test Results: No substantial differences in blood values were noted for most nutrients in dogs. However, vegan cats showed significantly lower levels of folic acid compared to those on conventional diets. The study identified some vegan pet foods that did not meet recommended dietary standards, highlighting potential risks of inadequate nutrient intake. Nutritional Adequacies and Concerns: While most homemade and commercial vegan diets seemed to fulfill basic nutritional needs for dogs, certain essential nutrients like methionine, cysteine, vitamin B12, and sodium were underrepresented in some cases. Cats, due to their specific metabolic and dietary requirements, might be less suited to a vegan diet. Essential nutrients such as taurine, arachidonic acid, and vitamin A must be supplemented to prevent deficiencies.