ORIGINAL RESEARCH Domestic dogs maintain positive clinical, nutritional, and hematological health outcomes when fed a commercial plant -based diet for a year Annika Linde, DVM, PhD, MPH1, Maureen Lahiff, PhD2, Adam Krantz, MS, DVM1, Nathan Sharp, BSc1, Theros T. Ng, PhD1, Tonatiuh Melgarejo, DVM, MS, PhD1 Author affiliations : 1 Western University of Health Sciences, College of Veterinary Medicine, Pomona, California 2 University of California Berkeley, School of Public Health, Berkeley, California Correspondence Tonatiuh Melgarejo, DVM, MS, PhD. Western University of Health Sciences (WesternU), College of Veterinary Medicine, 309 E. Second Street, Pomona CA 91766. Email: tmelgarejo@westernu.edu Annika Linde, DVM, PhD, MPH. Western University of Health Sciences, College of Veterinary Medicine, 309 E. Second Street, Pomona CA 91766. Email: alinde@westernu.edu ABSTRACT Objective : Domestic dogs can maintain health on complete and well-balanced canine plant-
based nutrition (K9PBN). Novel insight on health outcomes in dogs consuming K9PBN is of relevance to veterinary professionals and consumers given a growing interest in non-traditional dog foods with perceived health benefits, while considering potential safety concerns. We aimed to investigate nutritional equivalence by measuring clinical health outcomes in adult dogs fed K9PBN over twelve months compared to a meat-based diet at baseline. Animals : Fifteen clinically healthy adult dogs living in households in Los Angeles County, California. Procedures : Prospective cohort study evaluating clinical, hematological, and nutritional parameters in dogs at 0, 6, and 12 months, including complete blood count (CBC), blood chemistry, cardiac biomarkers, plasma amino acids, and serum vitamin concentrations. Results : Clinically healthy, client-owned, adult dogs maintain health, based on physical exams, CBC, serum chemistry, plasma amino acids, serum vitamins, and cardiac biomarkers combined with client-reported observations, when fed commercial K9PBN over a twelve-month period. Clinical Relevance : This study is the most comprehensive and longest known K9PBN investigation to date. It provides clinically important evidence-based nutrition data and new knowledge on outcomes in clinically healthy dogs who maintain health without consumption of animal-derived ingredients. Also , it is of major relevance to One Health paradigms since ingredients produced independent of industrial food animal production are both more sustainable and help to circumvent ethical dilemmas for maintenance of health in domestic dogs. INTRODUCTION Canine health relies on species-appropriate nutrition that aligns with different life stage requirements to optimize immune function while resisting disease-promoting stressors and dangers and also remaining cognizant that determinants of health span across five domains, including genetics, behaviors, environmental exposures, health care, and social circumstance s 1 . In comparison to the carnivorous wolf ( Canis lupus ), the domestic dog ( Canis familiaris ) is an omnivore species based on phylogenetic context and key anatomical-physiological traits 2. Evolutionary adaptations have resulted in a digestive system that enables dogs to maintain hea lth on nutritionally complete omnivorous diets, including those free of animal ingredients - demonstrating dogs have nutrient, not ingredient, requirements 3. Compared to the digestive capabilities of its ancestors, the domestic dog has developed adaptations in carbohydrate metabolism that enable more effective starch digestion 4. This important adaptation also enabled dogs to continue their co-existence with early humans during the agricultural revolution. The result is reflected in modern dogs, where even canine endurance athletes are able to maintain a high level of performance without animal-derived products in their diet 5. Increasing awareness of industrial food animal production’s central role in driving accelerated anthropogenic climate change, environmental degradation, disease patterns as well as social injustices, has im pacted consumer behaviors and fueled a growing interest in products developed without animal-sourced ingredients 3, 6. Changing societal trends have created an increasing demand for non-conventional dog foods, which has also triggered questions about the nutritional adequacy of such diets and their impact on cardiac and other health outcomes in canine consumers 7-12. While short-term studies have supported the adequacy of K9PBN 3, 5, 13, the need for long-term studies has remained. Bridging this knowledge gap served as the rationale driving this study. The study aim was to assess nutritional equivalence by measuring long-term health outcomes through evaluation of clinical, hematological, and nutritional parameters in clinically healthy adul t dogs fed a well-balanced, high-quality, commercial plant-based diet with pea protein as a main ingredient over twelve months as compared to commercial meat-based diets at baseline. For t he purpose of this study, the term “meat-based” is defined as a product with animal-derived protein sources regardless of if the product contains plant-derived ingredients. The term “plant-based” is defined as a product with plant-derived protein sources without animal-derived protein sources. The term “high quality” refers to alignment with AAFCO nutrient profiles (adult maintenance). The overall hypothesis fueling the study is that parameters of clinical health are maintaine d within normal limits after a year of consuming K9PBN. We conclude clinically healthy, adult, dogs can maintain health over a longer period of time when using a complete K9PBN approach. MATERIALS AND METHODS Study design A within-subject design with repeated measures was used for quarterly assessment of health status in fifteen adult dogs fed commercial K9PBN between January 2020 and January 2021. All dogs were fed different commercial meat-based diets for at least one year prior to enrollment, allowing individuals to serve as their own controls and strengthen the precision of the study. Clinically healthy canine participants were prospectively identified by emailing all stude nts, staff, and faculty at Western University of Health Sciences (WesternU) in California. The study was approved by the Western U Institutional Animal Care and Use Committee (R18IACUC014) with client consent obtained for all participating dogs prior to enrollment in the study. Incentives included a one-year supply of the study diet plus plant-based treats (V-Dog Kind Kibble and
