Efficacy of Vitamin D 2 in maintaining serum total vitamin D concentrations and bone mineralization in adult dogs fed a plant-based (vegan) diet in a three-month randomized trial.

Dogs are considered omnivores based on their evolution, consuming diets that include animal tissue. Few feeding trials evaluating the nutritional suitability of exclusively plant-based (vegan) diets in dogs have been published, and the efficacy of vitamin D 2 in maintaining canine serum vitamin D levels has not been clearly determined. A blinded dietary trial included 61 healthy desexed adult dogs: 31 fed an experimental extruded vegan diet (PLANT) and 30 fed a commercial extruded meat-based diet (MEAT) for three months. Dogs were screened via veterinary examination and routine laboratory analyses prior to enrolment in the study, at baseline and exit timepoints. Body composition was measured by dual-energy x-ray absorptiometry and blood was collected for vitamin D profiling. All dogs maintained health parameters, body weight and composition throughout the study. Dogs maintained on PLANT demonstrated a significant reduction in platelet count, creatinine, blood urea nitrogen and cholesterol, though values remained within normal reference ranges. Dogs fed PLANT also demonstrated a shift from vitamin D 3 to vitamin D 2 metabolites, though total vitamin D analogue levels were unchanged, with the exception of 24,25-dihydroxyvitamin D. Bone mineral content and density did not differ from baseline values. Health status was maintained in dogs fed PLANT and vitamin D 2 appeared efficacious in maintaining serum total vitamin D concentrations and bone mineralization. Findings support the hypothesis that PLANT was comparable to MEAT for maintenance of healthy adult dogs for at least three months and identified areas where further research is warranted to elucidate the potential risks and benefits of exclusively plant-based vegan diets.