PLANT-BASED NUTRITION RESEARCH
Can plant-based canine diets provide complete nutrition?
Dogs do not have a dietary requirement for any specific ingredients but rather need to consume appropriate amounts of 35+ essential nutrients. Essential nutrients include proteins, fats, vitamins, and minerals that must be provided by the diet. Many nutrients can be endogenously produced - i.e. created from other nutrients and substances within the body - so only the subset that forms the ‘building blocks’ and cannot be synthesized from other nutrients is considered essential.
U.S. (AAFCO) and European (FEDIAF) regulatory agencies establish nutritional profiles that include minimum (and sometimes maximum) amounts of every essential nutrient dogs require based on a consensus of current nutritional research. Every dog food that is labeled as “complete and balanced” for dogs of that life stage must meet those nutritional profile requirements for essential nutrients. Those guidelines provide the acceptable range, which allows for very different macronutrient approaches (e.g. high-meat / low-carb and meat-free / high fiber) that can all meet the standards. Choosing certain ingredient restrictions - like eliminating animal-derived products or avoiding grains - creates nutritional tradeoffs that diet formulators must address to ensure that all nutrients are present in adequate amounts.
Certain nutrients are present in small quantities (or absent) in plant-based ingredients, including vitamin B12 and the amino acid taurine. However, all essential nutrients have supplemental vegan sources. For example, vitamin B12 can only be made by bacteria that are present in the gut microbiome, which requires wild foraging and the ingestion of the mineral cobalt in soil to be synthesized "naturally." Vitamin B12 is only present in intensively farmed meat (which lacks access to consistent forage) because a bacteria-derived vitamin B12 supplement is added to livestock feed.
Expert pet food formulators carefully plan a diet to utilize ingredients that account for all nutritional needs, and the nutritional profile can then be confirmed with in-depth laboratory testing. Plant-based diets have been validated to provide all essential nutrients in canine diets.
Plant-based diets for dogs
Dodd SAS, Adolphe JL, Verbrugghe A. Plant-based diets for dogs. J Am Vet Med Assoc. 2018 Read
Trends in companion animal nutrition often mirror trends in human nutrition, reflecting the desire of pet owners to feed diets that they consider healthy and beneficial for the well-being of their pets. The number of people choosing to eat a plant-based diet and adopting a vegan lifestyle has been steadily increasing as individuals seek a lifestyle that they perceive to be healthier and with less impact on animals and the environment. It has been suggested that eliminating meat from the diet is more prevalent among pet owners than for the general public. Many of these meat-avoiding individuals have a moral dilemma regarding the husbandry of carnivorous pets: they avoid animal products in their own diet, but they live with pets that rely on nutritional sustenance from products derived from other animals.
Interest in, and availability of, plant-based diets are growing in popularity in the North American pet food market, but there are little data to support the benefits of feeding plant-based diets to omnivorous and carnivorous pets. For dogs, most essential nutrients can be obtained from plant sources. However, dogs evolved while eating an omnivorous diet that was high in animal tissues, which leads to concerns about whether plant-based diets can completely satisfy the nutritional requirements of dogs. Few studies have been conducted to examine the nutritional sufficiency of plant-based diets. Investigators of published studies simply evaluated the content of some nutrients in plant-based diets or evaluated a limited number of health variables in dogs fed plant-based diets.
The purpose of the information reported here was to address nutrients of concern when formulating plant-based diets and how to satisfy nutrient requirements of dogs without the use of animal-derived ingredients. It was intended to assist veterinarians when evaluating plant-based diets and providing guidance to pet owners who wish to feed their dogs such diets.
A comparison of key essential nutrients in commercial plant-based pet foods sold in Canada to American and European canine and feline dietary recommendations
Dodd SAS, Shoveller AK, Fascetti AJ, Yu ZZ, Ma DWL, Verbrugghe A. Animals (Basel). 2021 Aug 9;11(8):2348. Read
Plant-based foods intended for feeding dogs and cats are available in Canada, though few studies have examined the suitability of plant-based foods for dogs and cats. All commercial plant-based extruded and wet pet food products available in Ontario, Canada, in 2018 (n = 26) were acquired and analysed for energy, crude protein, crude fat, crude fibre, ash, amino acids, fatty acids, minerals and vitamins A, B12, D2 and D3. Results were compared with recommendations of the Association of American Feed Control Officials (AAFCO) and the European Pet Food Industry Federation (FEDIAF). Thirteen products were labelled for adult canine maintenance, four for canine all life stages, one for puppy growth, two for adult feline maintenance, three for feline all life stages, one for adult maintenance of dogs and cats and two for all life stages of dogs and cats. Four products met AAFCO and one product met FEDIAF nutrient recommendations for canine maintenance. No diets met AAFCO or FEDIAF recommendations for feline maintenance or growth for either species. Nutrients most commonly found insufficient were: sulfur amino acids, taurine, arachidonic acid, EPA and DHA, calcium phosphorus and vitamin D. There were no nutrients unable to be provided from non-animal sources. Compliance with labelling guidelines was also poor, similar to other findings with commercial animal-based pet products. The results from this study indicate areas where producers of plant-based pet foods must improve to meet the industry recommended nutrient profiles and labelling requirements.
Are plant-based diets "biologically appropriate"?
One way to understand the nutritional effects and suitability of different diets is through dogs’ digestive response and physiology. Certain enzymes and gut bacteria are critical to breaking down and digesting specific nutrients, and the presence (or lack) of digestive substances can be a critical first indication of a dog's ability to derive nutrition from certain foods. Digestibility refers to the efficiency with which the nutrients in food are absorbed and able to be incorporated into the body. Digestibility is important to consider when formulating foods, as certain nutrients (and most commonly protein) must be over-provisioned to account for the portion that is not digested and bioavailable. However, an ingredient with very high digestibility is not necessarily a benefit, as many nutrients like dietary fiber are difficult (or impossible) to digest but provide a variety of digestive and nutritional benefits. For example, ultra-processed foods like refined grains are often extremely digestible because they’ve been stripped of fiber and broken down into simple starches and sugars, which results in a very high glycemic load. A significant portion of American dogs are considered overweight or obese, which suggests an overabundance of digestible calories is the most prevalent nutritional problem.
The evolutionary history and genetic adaptations of canines also provide information about the digestive system and dietary patterns, although evolutionary pressures do not necessarily select for beneficial health outcomes and survival beyond reproduction. Physiological changes in dogs have been uniquely impacted by their relationship with humans, particularly in the past few centuries as humans have implemented selective breeding to suit human preferences that are often in direct opposition to health and well-being (such as brachycephalic traits). However, co-evolution with humans has also resulted in the strengthening of omnivorous traits and consumption of plant-based foods. The following evidence suggests the suitability of plant-based canine diets:
Dogs digest common plant-based ingredients - and their proteins - at a high rate.
Experimental digestibility studies have measured the total digestibility, protein digestibility, and specific amino acid digestibility of different plant-based proteins and well as complete canine diets, including fresh vegan diets. The digestibility of the tested plant-based canine formulas are consistently high and often higher than traditional meat-inclusive kibble.
Dogs have evolved to digest starch and carbohydrates at higher rates than their common wolf ancestor.
Dogs developed significant genetic adaptations to digest starches with high efficiency, which occurred at the same time that humans began large-scale cultivation of cereals ~3,000-5,000 years ago. The enhanced ability to derive nutrients from carbohydrates is one of the primary genetic differences between companion dogs and wolves.
Dogs have eaten plant-rich diets for thousands of years.
Archeological evidence support the hypothesis that dogs consumed diets that were highly correlated with the diets of local humans (either intentionally prepared for the dogs or as scavenged trash), including consuming almost entirely plant-based diets in Europe and the Middle East where meat was rare and costly and humans primarily subsisted on grains and legumes. Interestingly, even wolves eat more plants and human food than conventional wisdom would suggest, and particularly those that live in close proximity to humans.
While dogs are members of the order Carnivora (i.e. they are carnivorans), they are not obligate carnivores.
Most dogs are opportunistic scavengers and will eat food that is available. Many carnivorans have distinct dietary habits, including omnivorous scavengers like raccoons and even herbivorous panda bears that began consuming significant amounts of protein almost exclusively through plant-based sources in the last 5,000-10,000 years. Studies have found that dogs are not born with an innate preference for meat, but may develop a preference for protein-rich foods in a nutrient-limited environment (such as the stray street dogs included in the study).
The genomic signature of dog domestication reveals adaptation to a starch-rich diet
Axelsson, E., Ratnakumar, A., Arendt, ML. et al. Nature 495, 360–364 (2013). Read
The domestication of dogs was an important episode in the development of human civilization. The precise timing and location of this event is debated and little is known about the genetic changes that accompanied the transformation of ancient wolves into domestic dogs. Here we conduct whole-genome resequencing of dogs and wolves to identify 3.8 million genetic variants used to identify 36 genomic regions that probably represent targets for selection during dog domestication. Nineteen of these regions contain genes important in brain function, eight of which belong to nervous system development pathways and potentially underlie behavioural changes central to dog domestication6. Ten genes with key roles in starch digestion and fat metabolism also show signals of selection. We identify candidate mutations in key genes and provide functional support for an increased starch digestion in dogs relative to wolves. Our results indicate that novel adaptations allowing the early ancestors of modern dogs to thrive on a diet rich in starch, relative to the carnivorous diet of wolves, constituted a crucial step in the early domestication of dogs.
Amino acid digestibility and nitrogen-corrected true metabolizable energy of mildly cooked human-grade vegan dog foods using the precision-fed cecectomized and conventional rooster assays
Leah J Roberts, Patricia M Oba, Pamela L Utterback, Carl M Parsons, Kelly S Swanson. Translational Animal Science, Volume 7, Issue 1, 2023, txad020, Read
The pet food market is constantly changing and adapting to meet the needs and desires of pets and their owners. One trend that has been growing in popularity lately is the feeding of fresh, human-grade foods. Human-grade pet foods contain ingredients that have all been stored, handled, processed, and transported in a manner that complies with regulations set for human food production. While most human-grade pet foods are based on animal-derived ingredients, vegan options also exist. To our knowledge, no in vivo studies have been conducted to analyze the performance of human-grade vegan diets. Therefore, the objective of this study was to investigate the amino acid (AA) digestibility and nitrogen-corrected true metabolizable energy (TMEn) of mildly cooked human-grade vegan dog foods using precision-fed cecectomized rooster and conventional rooster assays. Three commercial dog foods were tested. Two were mildly cooked human-grade vegan dog diets (Bramble Cowbell diet (BC); Bramble roost diet (BR)), while the third was a chicken-based extruded dog diet (chicken and brown rice recipe diet (CT)). Prior to the rooster assays, both mildly cooked diets were lyophilized, and then all three diets were ground. Diets were fed to cecectomized roosters to determine AA digestibility, while conventional roosters were used to determine TMEn. All data were analyzed using the mixed models procedure of SAS (version 9.4). The majority of indispensable and dispensable AA across all diets had digestibilities higher than 80%, with a few exceptions (BC: histidine, lysine, threonine, and valine; BR: histidine). The only difference in indispensable AA digestibility among diets was observed with tryptophan, with its digestibility being higher (P = 0.0163) in CT than in BC. TMEn values were higher (P = 0.006) in BC and BR (4.55 and 4.66 kcal/g dry matter, respectively) than that in CT (3.99 kcal/g dry matter). The TMEn/GE was also higher (P = 0.0193) in BR than in CT. Metabolizable energy (ME) estimates using Atwater factors accurately estimated the energy content of CT, but modified Atwater factors and the predictive equations for ME recommended by the National Research Council underestimated energy content. All calculations underestimated the measured TMEn values of BC and BR, with Atwater factors being the closest. Although testing in dogs is required, these data suggest that mildly cooked human-grade vegan dog diets are well-digested. Moreover, TMEn data suggest that existing methods and equations underestimate the ME of the mildly cooked human-grade vegan foods tested.
Dogs that ate plants: Changes in the canine diet during the late Bronze Age and the first Iron Age in the northeast Iberian Peninsula
Silvia Albizuri, Aurora Grandal dʼAnglade, Julià Maroto, Mònica Oliva, Alba Rodríguez, Noemí Terrats, Antoni Palomo, F. Javier López Cachero. Journal World Prehistory, March, 2021. Read
We studied 36 dogs (Canis familiaris) from the Can Roqueta site in the Catalan pre-littoral depression (Barcelona), dated between the Late Bronze Age and the First Iron Age (1300 and 550 cal BC). We used a sample of 27 specimens to analyse the evolution of the dogs’ diet based on the carbon δ13C and nitrogen δ15N isotope composition. The results show a marked human influence in that these natural carnivores display a highly plant-based diet. The offset between canids and herbivorous ungulates does not reach the minimum established for a trophic level, which implies an input of C3 and C4 (millet) cultivated plants. Moreover, the homogeneity in the values indicates that humans prepared their dogs’ food.
Preference for meat is not innate in dogs
Bhadra A and Bhadra A. Journal of Ethology 2014; 32:15-22. Read
Indian free ranging dogs live in a carbohydrate rich environment as scavengers in and around human settlements. They rarely hunt and consequently do not encounter rich sources of protein. Instead they have adapted to a diet of primarily carbohydrates. As descendants of the exclusively carnivorous wolves, they are subjected to the evolutionary load of a physiological demand for proteins. To meet their protein needs they resort to a thumb rule, if it smells like meat, eat it. Pups face high competition from group and non group members and are in a phase of rapid growth with high protein demands. Following the thumb rule, then they can acquire more protein at the cost of increased competition and reduced supplementary non protein nutrition. However, if the mother supplements their diet with protein rich regurgitates and milk, then the pups can benefit by being generalists. Using a choice test in the field we show that while adults have a clear preference for meat, pups have no such preference, and they even eat degraded protein eagerly. Thus the thumb rule used by adult dogs for efficient scavenging is not innate, and needs to be learned. The thumb rule might be acquired by cultural transmission, through exposure to meat in the regurgitate of the mother, or while accompanying her on foraging trips.
Macronutrient composition, true metabolizable energy and amino acid digestibility, and indispensable amino acid scoring of pulse ingredients for use in canine and feline diets
Lauren M Reilly, Patrick C von Schaumburg, Jolene M Hoke, Gary M Davenport, Pamela L Utterback, Carl M Parsons, Maria R C de Godoy. Journal of Animal Science, Volume 98, Issue 6, June 2020, skaa149, Read
The rising consumer demand for alternative and sustainable protein sources drives the popularity of the use of plant-based proteins in the pet food industry. Pulse crops, which include beans, peas, lentils, and chickpeas, have become an important addition to both human and animal diets due to their protein content and functional properties. However, knowledge of their nutrient composition and protein quality is necessary for the proper formulation of these ingredients in pet foods. The objective of this study was to determine the macronutrient composition and standardized amino acid digestibility and to describe the protein quality through the use of digestible indispensable amino acid scores (DIAAS-like) of five pulse ingredients. Black bean (BB) grits, garbanzo beans (GB), green lentils (GL), navy bean (NB) powder, and yellow peas (YP) were analyzed for dry matter (DM), ash and organic matter (OM), crude protein (CP), gross energy (GE), acid hydrolyzed fat (AHF), and total dietary fiber (TDF) to determine the macronutrient composition. Precision-fed rooster assays were conducted using cecectomized roosters to calculate standardized amino acid digestibility and true metabolizable energy corrected for nitrogen (TMEn). The essential amino acids, with the exception of methionine, were highly digestible with digestibility values of 80% to 90% (dry matter basis) for all selected pulse ingredients. BB grits had the lowest (P < 0.05) digestibility of arginine (86.5%) and histidine (80.6%) in contrast to GB (94.9% and 89.9%, respectively). The TMEn of GB was highest (P < 0.05) at 3.56 kcal/g compared with the other pulses. The DIAAS-like values for adult dogs were consistently the lowest for methionine for all pulses, making it the first-limiting amino acid in these ingredients. The DIAAS-like values for adult cats showed GL had lowest (P < 0.05) score in tryptophan compared with other pulses when using both AAFCO values and NRC recommended allowances as reference proteins. Methionine was the first-limiting amino acid for YP and tryptophan for GL. Based on macronutrient composition, protein quality, and amino acid digestibility, it can be concluded that pulse ingredients have the required nutritional characteristics to be viable protein sources in canine and feline foods. However, the use of complementary protein sources is recommended to counterbalance any potential limiting amino acids in pulse ingredients.
Adaptive diet strategy of the wolf (Canis lupus L.) in Europe: a review
Silvia Albizuri, Aurora Grandal dʼAnglade, Julià Maroto, Mònica Oliva, Alba Rodríguez, Noemí Terrats, Antoni Palomo, F. Javier López Cachero. Journal World Prehistory, March, 2021. Read
The diet strategy of the wolf in Europe is reviewed on the basis of 74 basic and 14 additional literature sources. The comparative analysis reveals clear dependence on the latitude (and, therefore, on the changing environmental conditions) correlated with the wild ungulate abundance and diversity. Following a geographic pattern, the wolf is specialised on different species of ungulates: moose and reindeer in Scandinavia, red deer in Central and Eastern Europe and wild boar in Southern Europe. Where this large prey is taken, the roe deer is hunted with almost the same frequency in every region. The wolf diet in Europe shows two ecological adaptations formed by a complex of variables: 1. Wolves living in natural habitats with abundance of wild ungulates feed mainly on wild prey. 2. In highly anthropogenic habitats, with low abundance of wild prey, wolves feed on livestock (where husbandry of domestic animals is available) and take also a lot of plant food, smaller prey (hares and rodents) and garbage food. The frequency of occurrence of wild ungulates in the diet of wolves in North Europe varies from 54.0% in Belarus to 132.7% in Poland, while that of livestock is in the range from 0.4% in Norway to 74.9% in Belarus. In South Europe, the frequency of occurrence of wild prey varies from 0% in Italy and Spain to 136.0% in Italy, while of domestic ungulates ranges between 0% and 100% in Spain. The low density or lack of wild prey triggers the switch of the wolf diet to livestock, plant food (32.2-85% in Italy) or even garbage (up to 41.5% in Italy).
Can dogs thrive on a plant-based diet?
A significant evidence base of clinical, experimental, and epidemiological analyses demonstrates that a properly formulated (AAFCO-compliant) plant-based diet provides dogs with equivalent - and even superior - health outcomes compared to dogs eating a meat-inclusive diet.
The existing research has largely focused on searching for nutritional deficits rather than prospective benefits, and a systematic review of all relevant published studies found that “there is little evidence of adverse effects arising in dogs and cats on vegan diets. Additionally, there is some evidence of benefits, particularly arising from guardians’ perception of the diets.”
Owners of dogs eating plant-based diets have consistently reported better health outcomes - and longer average lifespans - than dogs eating traditional meat-inclusive diets. A recent analysis of owner-reported health information for more than 1,400 dogs found that dogs eating plant-based diets had longer reported lifespans (>1 additional year) and fewer reported health issues than dogs that consumed traditional diets. Another study that included over 2,500 dogs found that dogs eating plant-based diets had fewer reported health issues - including irregular veterinary visits and medication use - than dogs eating either conventional meat-inclusive diets or raw meat diets. While owner-reported health data have bias and accuracy issues, owner-reported metrics are widely used in veterinary epidemiology as the most accessible form of population health information and lack of standardized health (or death) records in veterinary care.
Many controlled experiments in which groups of dogs are fed either a plant-based or a meat-inclusive diet have also shown no adverse health outcomes in plant-based groups. That includes a long-term trial that monitored companion dogs’ wellness - including physical exams, blood chemistry, and cardiac biomarkers - for over 12 months after transitioning from meat-inclusive to plant-based diets and concluded that “clinically healthy, adult dogs can maintain health over a longer period of time when using a complete plant-based diet approach.” Another experiment found that dogs participating in 12 weeks of intense physical activity (sled racing) demonstrated no significant differences in blood health biomarkers when eating a plant-based vs. meat-inclusive diet.
In addition, an experimental trial found that plant-based diets improved the gut microbiome of dogs with chronic gastrointestinal inflammation. Randomized experimental trials have also found that dogs transitioned to plant-based diets demonstrated reductions in blood platelets, cholesterol, and biomarkers associated with kidney function compared to dogs on a control meat-inclusive diet, although both groups remained in healthy reference ranges. The changes in these metabolic markers are consistent with the results of human experimental studies of plant-based diets and have been interpreted as a reduction in both inflammation and risk factors for kidney disease.
The impact of vegan diets on indicators of health in dogs and cats: A systematic review
Domínguez-Oliva, A.; Mota-Rojas, D.; Semendric, I.; Whittaker, A.L. Vet. Sci. 2023, 10, 52. Read
There has been controversy within the scientific literature, and in the popular press and online media, around the safety of feeding vegan diets to dogs and cats. With an increase in adherence to meat-free diets in the human population, many guardians may be considering providing these diets to their companion animals. Concerns arise due to dog and cat gut physiology which has adapted to a complete meat-based diet (cats) or largely meat-based diet (dogs). Particular concerns have been raised around deficiencies in certain amino acids such as taurine, and vitamins such as B12 (cobalamin) and B9 (folate). To date, there has been no formal assimilation of the scientific evidence on this topic, with a focus on actual health impacts of diets, as opposed to nutritional composition. In this review, we conducted a formal assessment of the evidence in the form of a systematic review. We found that there has been limited scientific study on the impact of vegan diets on cat and dog health. In addition, the studies that have been conducted tended to employ small sample sizes, with study designs which are considered less reliable in evidence-based practice. Whilst there have been several survey studies with larger sample sizes, these types of studies can be subject to selection bias based on the disposition of the respondents towards alternative diets, or since answers may relate to subjective concepts such as body condition. However, there is little evidence of adverse effects arising in dogs and cats on vegan diets. In addition, some of the evidence on adverse health impacts is contradicted in other studies. Additionally, there is some evidence of benefits, particularly arising from guardians’ perceptions of the diets. Given the lack of large population-based studies, a cautious approach is recommended. If guardians wish to implement a vegan diet, it is recommended that commercial foods are used.
Owner perception of health of North American dogs fed meat- or plant-based diets
Dodd, Sarah & Khosa, Deep & Dewey, Cate & Verbrugghe, Adronie. (2022). Research in Veterinary Science. 149. Read
Some dog owners elect to feed their dog a plant-based food either as part of or for their entire dietary intake. Being omnivores or facultative carnivores, a strictly plant-based diet is not the natural type of food dogs evolved to consume, leaving some question as to whether this feeding management strategy is safe and healthy for dogs. This study surveyed owner perceptions of health and wellbeing of dogs and compared between those fed meat-based and plant-based diets. A web-based questionnaire was distributed to pet owners to collect data on dog characteristics, husbandry, health and wellbeing. Univariate comparisons between diet groups was made by chi square analyses or Kaplan-Meier tests as appropriate, with a significance cut-off value of 0.05. Multivariate models were negative binomial and logistic regression for count and categorical data, respectively. Owners feeding plant-based diets to their dog reported fewer health disorders, specifically with respect to ocular or gastrointestinal and hepatic disorders. Dog longevity was reported to be greater for dogs fed plant-based diets. Owners feeding plant-based diets to their dogs relied less on veterinary associates for nutrition information, versus dog owners feeding meat-based diets. Dog owners feeding a plant-based diet did not perceive adverse health effects in their dogs. The results might suggest an association between feeding a plant-based diet and perceived health and longevity, however inherent bias and limitations associated with surveys of owner perception must be considered, and objective research is required to determine if plant-based diets truly affect canine health.
Vegan versus meat-based dog food: Guardian-reported indicators of health
Knight A, Huang E, Rai N, Brown H (2022) PLOS ONE 17(4): e0265662. Read
Alternative pet foods may offer benefits concerning environmental sustainability and the welfare of animals processed into pet foods. However, some worry these may compromise the welfare of pets. We asked 2,639 dog guardians about one dog living with them, for at least one year. Among 2,596 involved in pet diet decision-making, pet health was a key factor when choosing diets. 2,536 provided information relating to a single dog, fed a conventional meat (1,370 = 54%), raw meat (830 = 33%) or vegan (336 = 13%) diet for at least one year. We examined seven general indicators of ill health: unusual numbers of veterinary visits, medication use, progression onto a therapeutic diet after initial maintenance on a vegan or meat-based diet, guardian opinion and predicted veterinary opinion of health status, percentage of unwell dogs and number of health disorders per unwell dog. Dogs fed conventional diets appeared to fare worse than those fed either of the other two diets. Dogs fed raw meat appeared to fare marginally better than those fed vegan diets. However, there were statistically significant differences in average ages. Dogs fed raw meat were younger, which has been demonstrated to be associated with improved health outcomes. Additionally, non-health related factors may have improved apparent outcomes for dogs fed raw meat, for three of seven general health indicators. We also considered the prevalence of 22 specific health disorders, based on predicted veterinary assessments. Percentages of dogs in each dietary group considered to have suffered from health disorders were 49% (conventional meat), 43% (raw meat) and 36% (vegan). Significant evidence indicates that raw meat diets are often associated with dietary hazards, including nutritional deficiencies and imbalances, and pathogens. Accordingly, the pooled evidence to date indicates that the healthiest and least hazardous dietary choices for dogs, are nutritionally sound vegan diets.
Domestic dogs maintain positive clinical, nutritional, and hematological health outcomes when fed a commercial plant-based diet for a year
Annika Linde, Maureen Lahiff, Adam Krantz, Nathan Sharp, Theros T. Ng, Tonatiuh Melgarejo. bioRxiv 2023.02.18.525405; Read
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. Fifteen clinically healthy adult dogs living in households in Los Angeles County, California.
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. 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. 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.
An experimental meat-free diet maintained haematological characteristics in sprint-racing sled dogs
Brown, W., Vanselow, B., Redman, A., & Pluske, J. (2009). British Journal of Nutrition, 102(9), 1318-1323. Read
A dog's nutrient requirements can theoretically be met from a properly balanced meat-free diet; however, proof for this is lacking. Exercise places additional demands on the body, and dogs fed a meat-free diet may be at increased risk of developing sports anaemia. We hypothesised that exercising dogs would remain in good health and not develop anaemia when fed a nutritionally balanced meat-free diet. To this end, twelve sprint-racing Siberian huskies were fed either a commercial diet recommended for active dogs (n 6), or a meat-free diet formulated to the same nutrient specifications (n 6). The commercial diet contained 43 % poultry meal, whereas soyabean meal and maize gluten made up 43 % of the meat-free diet, as the main protein ingredients. Dogs were fed these diets as their sole nutrient intake for 16 weeks, including 10 weeks of competitive racing. Blood samples were collected at weeks 0, 3, 8 and 16, and veterinary health checks were conducted at weeks 0, 8 and 16. Haematology results for all dogs, irrespective of diet, were within normal range throughout the study and the consulting veterinarian assessed all dogs to be in excellent physical condition. No dogs in the present study developed anaemia. On the contrary, erythrocyte counts and Hb values increased significantly over time (P < 0·01) in both groups of dogs. The present study is the first to demonstrate that a carefully balanced meat-free diet can maintain normal haematological values in exercising dogs.
Short-term amino acid, clinicopathologic, and echocardiographic findings in healthy dogs fed a commercial plant-based diet
Cavanaugh SM, Cavanaugh RP, Gilbert GE, Leavitt EL, Ketzis JK, et al. (2021) PLOS ONE 16(10): e0258044. Read
Consumer demand for commercially prepared plant-based (PB) dog food is increasing, but studies evaluating the short- or long-term effects of PB diets on canine health are lacking. The objective of this study was to assess the short-term amino acid (AA), clinicopathologic, and echocardiographic findings in 34 client-owned dogs fed a commercial extruded plant-based diet (PBD) in which pea protein was the primary protein source and 4 control dogs fed a commercial extruded traditional diet (TD). Plasma AA and whole blood taurine concentrations were measured in dogs at baseline and after 4 weeks on the PBD or the TD. Hematologic, serum biochemical, and echocardiographic testing were performed at baseline and after 12 weeks on the PBD or the TD. Four dogs in the PBD group did not complete the study. All essential AAs, except methionine, were higher in dogs after 4 weeks on the PBD compared to baseline. Taurine (plasma and whole blood) was also higher after 4 weeks on the PBD compared to baseline. A meaningful difference was detected in whole blood taurine between the PBD group and the control group at 4 weeks (P = .026) with the PBD group being higher. Median hematologic and biochemical results for the PBD group were within normal limits at baseline and at 12 weeks. In the PBD group, left ventricular internal diastolic dimension (LVIDd, P = < .001) and normalized LVIDd (P = .031) were higher 12 weeks post-PBD compared to baseline. There were no meaningful differences in left ventricular internal systolic dimension (LVIDs), normalized LVIDs, or fractional shortening 12 weeks post-PBD. There was no statistical evidence of difference between the 2 groups of dogs for any of the echocardiographic parameters at baseline or at 12 weeks. Essential AA or taurine deficiency was not observed in this cohort of dogs fed a commercial extruded PBD. Additionally, clinically relevant hematologic, serum biochemical and echocardiographic alterations were not detected. Further research is required to determine if long-term static feeding of PB diets can meet and maintain AA and other nutrient targets in dogs.
Efficacy of vitamin D2 in maintaining serum total vitamin D concentrations and bone mineralisation in adult dogs fed a plant-based (vegan) diet in a 3-month randomised trial
Dodd, S., Adolphe, J., Dewey, C., Khosa, D., Abood, S., & Verbrugghe, A. (2023). British Journal of Nutrition, 1-15. Read
Dogs are considered omnivores based on their evolution consuming diets including 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 D2 in maintaining canine serum vitamin D levels has not been clearly determined. A blinded dietary trial included sixty-one healthy desexed adult dogs: thirty-one fed an experimental extruded vegan diet (PLANT) and thirty fed a commercial extruded meat-based diet (MEAT) for 3 months. Dogs were screened via veterinary examination and routine laboratory analyses prior to enrolment, 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 D3 to vitamin D2 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 D2 appeared efficacious in maintaining serum total vitamin D concentrations and bone mineralisation. Findings support the hypothesis that PLANT was comparable to MEAT for maintenance of healthy adult dogs for at least 3 months and identified areas where further research is warranted to elucidate the potential risks and benefits of plant-based (vegan) diets.
Vegan diet and its effects on the dogs' health
Kiemer, L. (2020). Lithuanian University of Health Sciences: Kaunas, Lithuania. Read
This research was conducted at the Department of Animal Husbandry in the Veterinary Academy of the Lithuanian University of Health Sciences in 2019. In this investigation, dogs in Scheer, Germany, were fed two different diets: vegan and meat-based. The nutritional adequacy of a vegan diet was determined by analysis of blood samples from 40 dogs, 20 of which were fed a 100% plant-based vegan diet for an average of 2.15 years, and a control group of 20 were fed a meat-based diet. The results showed the same number of surpluses in both groups; however, the vegan group had only two nutritional deficiencies compared to 11 in the meat fed group. Statistically significant differences (p < 0.01) were found between the groups in iron, vitamin B12 and folic acid concentrations. Total protein, calcium and magnesium were not significantly different (p > 0.05). To further evaluate the impact of a plant-based diet on dog health; eight dogs were put on a six-week feeding trial. The dogs were split into two groups of four dogs each; the control group was fed a meat-based diet, and the other group was fed a vegan diet. Blood analyses were performed prior to the start and at the end of the trial. The results showed that most of the values were not significantly changed. Some folic acid, B12 and iron deficiencies detected prior to the trial reached recommended healthy ranges during the trial on a vegan diet, although one dog experienced a folic acid surplus and another dog a folic acid deficiency. All participants from all groups were determined to be in overall good health or in a condition that would not affect the blood chemistry parameters. These included total protein, vitamin B12, folic acid, calcium, magnesium, iron, taurine and L-carnitine. Laboratories analysing blood samples in Germany were Laboklin (seven samples), EasyLAB (two samples), IDEXX (37 samples), SYNLAB (one sample); in Australia, ASAP LABORATORY (two samples); and in England, AXIOM VETERINARY LABORATORIES (two samples). Veterinarians performed physical examinations during blood sample collection in various cities in Germany (including Stuttgart and Regensburg), England (Newton Abbot) and Australia (Melbourne). To collect additional data from dog owners feeding a vegan or partially vegan diet, a questionnaire (initially presented to several thousand potential participants) was completed by 250 people. Blood chemistry analysis and physical examinations of the vegan dogs in this study together clearly indicate that a vegan diet can be healthy and adequate for dogs, and in some cases, even improve overall health. The additional data collected from 250 dog owners feeding a plant-based diet strongly supported this conclusion.
Effect of an extruded animal protein-free diet on fecal microbiota of dogs with food-responsive enteropathy
Bresciani F, Minamoto Y, Suchodolski JS, Galiazzo G, Vecchiato CG, Pinna C, Biagi G, Pietra M. J Vet Intern Med. 2018 Nov;32(6):1903-1910. Read
Dietary interventions are thought to modify gut microbial communities in healthy individuals. In dogs with chronic enteropathies, resolution of dysbiosis, along with remission of clinical signs, is expected with treatment. To evaluate changes in the fecal microbiota in dogs with food-responsive chronic enteropathy (FRE) and in healthy control (HC) dogs before and after an elimination dietary trial with an animal protein-free diet (APFD). Dogs with FRE (n = 10) and HC (n = 14). Dogs were fed the APFD for 60 days. Fecal microbiota was analyzed by Illumina 16S rRNA sequencing and quantitative polymerase chain reaction (PCR). A significantly lower bacterial alpha-diversity was observed in dogs with FRE compared with HC dogs at baseline, and compared with FRE dogs after the trial. Distinct microbial communities were observed in dogs with FRE at baseline compared with HC dogs at baseline and compared with dogs with FRE after the trial. Microbial communities still were different in FRE dogs after the trial compared with HC dogs at baseline. In HC dogs, the fecal microbiota did not show a significant modification after administration of the APFD. Our results suggest that, in FRE dogs, treatment with the APFD led to a partial recovery of the fecal microbiota by significantly increasing microbiota richness, which was significantly closer to a healthy microbiota after the treatment. In contrast, no changes were detected in the fecal microbiota of HC dogs fed the same APFD.
What testing has been performed on Petaluma diets?
Petaluma evaluates the nutritional quality of our diets with multiple analytical methods to validate that all essential nutrients are being provided (and digested) in appropriate amounts.
The team is also committed to testing protocols that treat dogs like family members rather than lab equipment. Petaluma does not perform any laboratory animal testing or contract other companies to test our products on laboratory animals and is a certified cruelty-free company by PETA. The company also preferentially sources ingredients from suppliers that do not test their products on animals.
Petaluma contracts veterinary nutrition experts to formulate the diets, which are first validated with software to ensure the estimated nutritional profile meets the nutritional standards of the life stage that it is intended for. The research team then produces a small batch of the food and conducts laboratory analyses to measure the levels of all 35 essential nutrients, plus some other important factors like dietary fiber. The company repeats the full essential nutrient analysis annually for each formula in addition to testing each batch for macronutrient and mineral content.
After the formulation team determines that the diet meets nutritional standards, the food is sent to over 50 beta testers who feed the diet to their companion dogs for at least 30 days - and most for 90+ days. Data are collected about how the dogs liked the taste, how it is impacting their digestion, and any observed changes in basic wellness indicators like scratching and energy levels.
For tests that are harder to perform with volunteer companion dogs, such as digestibility testing, Petaluma partnered with a university laboratory that developed and validated a cutting-edge in vitro technique that accurately models the digestive system of a dog without the need for laboratory animals. The laboratory has published studies to validate its methodology against more invasive in vivo testing and found that it provides an accurate gauge of bioavailability without the need for animal test subjects. Petaluma's diets were measured to have over 90% protein digestibility, which is higher than the average dog food formula that uses meat meal as a primary protein source. Petaluma contains more dietary fiber (~15% of dry matter) than typical dog food, which provides digestive benefits but lowers total dry matter digestibility as it is inherently indigestible by digestive enzymes.
Most pet food companies test their diets using corporate- or laboratory-owned dogs living in shelter-like environments. While many company-owned kennels provide high standards of care, we believe dogs belong in homes and are happy to invest additional time and money to conduct more compassionate testing.