This article first appeared with LinkedIn
In 2018, plant-based food sales in the US grew 11% vs. the previous year and surpassed $4.5 billion in sales. While vegan/vegetarian pet food sales did not crack the Top 10, it has seen significant interest and growth as a category. A 2015 study interviewed over 3,200 pet owners that identified themselves as vegan/vegetarian. In that sample, 39% fed a commercially available diet exclusively; 9% fed only homemade diets and the remaining 52% fed commercial diets with regular additions of homemade ingredients. While only 6% of Americans are vegan/vegetarian, 25% of 25-34 year olds identify as such. Since Millennials are now the largest pet owning generation, the implications are significant. As with most human food trends, pet food is sure to follow the plant-based path but can dogs really be fed vegan/vegetarian diets?
To determine pet owner attitudes and feeding practices, Sarah Dodd, DVSC (an independent veterinary consultant for Halo) surveyed 2,940 dog owners that were both meat-based feeders and plant-based (broken down further: 1.6% were exclusively vegan/vegetarian and 10.4% occasionally). The reasons given most often for choosing a plant-based diet: farm animal welfare/rights and environmental impact. Those opposed to vegetarian diets claim that dogs are carnivores and that plant-based diets are incomplete; lacking essential nutrients. While there are many more arguments on both sides, these are the ones cited most often.
While belonging to the Order Carnivora (the same as wolves, cats and 280 other placental mammals that eat meat), dogs are actually omnivores (facultative omnivores to be exact). This means that they can eat both meat-based and plant-based diets as opposed to obligate carnivores (like cats) that require nutrients only found in animal flesh.
"UNNATURAL/PHYSICAL ANATOMY" CLAIM
It is true that a dog's teeth were not made for lateral grinding (like humans or cows). They are most effective at tearing flesh from bone. Additionally, a dog's GI tract is very short. The smaller the gut capacity or ratio of gut length to body length, the faster the gut’s passage rate and the more nutrient-dense and easily digestible the animal’s diet must be in order for the animal to be able to obtain enough nutrients for survival (Demment & Van Soest, 1985). The small intestines (duodenum, ileum and jejunum) are where the majority of nutrient absorption takes place. Diets that are less digestible with high carbohydrates pass through too quickly and aren't properly broken down and absorbed (low bioavailability). This results in a lot of fecal volume and poor nutrition (Case et. al. 2014). So while their anatomy may not be "ideal", today's dogs have evolved to accept, digest and utilize whatever food is available. For example, today's meat-based dry kibble diets contain more than 35% carbohydrates (sometimes as high as 65%) whereas your dog's ancestors lived off of diets containing less than 10% carbohydrates.
"SAVING THE ENVIRONMENT" CLAIM
What about the idea that plant-based dog food can save the environment? This began with an erroneous report in 2006 from the United Nations Food and Agricultural Organization (FAO) that claimed animal agriculture was responsible for 65% of nitrous oxide, 37% of methane, 64% of ammonia and 9% of all carbon dioxide. All this, the study claimed, meant that livestock was responsible for 18% of total GHG! The problem was that the percentages were distorted because they used different methodologies when comparing the green house gas (GHG) emissions from different sectors. Henning Steinfeld, the original author of the study, submitted a correction using consistent methodologies that showed the Top 3 culprits of GHG were actually electricity production (28%), transportation (27%) and the industrial sector (22%). Plant agriculture came in at 5.1% and animal agriculture came in at 3.9%, globally. Higher GHG from plant agriculture makes sense considering that meat production in developing nations significantly trails that of the US and Europe. So while not "saving" the environment, any GHG reduction helps.
"ANIMAL WELFARE/RIGHTS" CLAIM
Now as for the social conscious regarding animal welfare and rights, I find that to be a very admirable trait and worthy of discussion. As demand for meat-based diets increases across developing nations, the efficiency of meat production continues to try to keep pace. Eventually however we will reach "critical mass" where demand surpasses supply and cost increases disproportionately. This is one of the reasons I serve as an Advisory Board member for Bond Pet. Rich Kelleman and his team are diligently working on a cultured meat solution for the pet space that incorporates the best of both worlds.
"LACKING NUTRIENTS" CLAIM
A study by Kanakubo et al. (2015) examined 13 dry and 11 canned vegetarian diets for dogs and cats that were sold in all or most of the United States. Crude protein (CP) and amino acid (AA) concentrations were compared with AAFCO Dog and Cat Food Nutrient Profiles. Twenty-five percent of diets (6/24), did NOT meet all of the essential amino acid minimum requirements despite stating they were "formulated to meet AAFCO requirements". This issue, while not addressed in the study, is not exclusive to plant-based diets alone and the same issues can be seen across meat-based diets as well. Kanakubo and colleagues contacted each of those companies by email. They inquired whether they had any additional data or information relevant to the conclusions of their findings. In particular, they asked whether companies could supply any evidence (e.g., studies by external independent laboratories or internal assessments) to verify the nutritional adequacy of their products. They also inquired about any steps taken during the manufacturing process to ensure that diets are nutritionally adequate, and consistent over time.
An initial email inquiry was followed by an additional email to non-responders after one month. Five companies failed to respond to either inquiry and one company declined to provide comment. Of those that responded, they all asserted that their products were nutritionally adequate.
- One stated that their diet is “formulated to meet or exceed the nutritional levels established by the AAFCO Dog Food Nutrient Profiles for adult maintenance”. They added that, “Our production facility has staffed animal nutrition experts and veterinarians that conduct regular tests on the kibble post production to ensure its nutritional adequacy. We obtained our kibble’s guaranteed analysis from an external lab and our regular nutrition and quality tests are performed by our production facility on a regular basis”. Although they do not run feeding/digestibility trials they said, “We’ve been in business for over 11 years and have seen thousands of dogs thrive into their golden years on [our diet]”.
- Another claims that, “In addition to independent laboratory tests for determining the level of vitamins, minerals and nutrients in our finished diets, we conduct home feeding studies to determine the performance of our diets in an actual home environment. We have done this for the past 20 years and are confident and pleased with our data that shows our diets perform, as a single source diet should, for the long term health and long life of our study group’s companions (average 16 years for canines and 18 years for felines)”. They added, “Our data is proprietary and we will not be able to share it with you."
- and a third admitted that its product was unlikely to be nutritionally complete: “[We do] not advocate the singular feeding of [our diet] to carnivores such as dogs and cats. … It is designed for intermittent feeding or as a base to add different meats for sensitivities and allergies”. They further asserted their philosophical opposition to the concept of attempting to produce a single, nutritionally complete diet: “Complete knowledge of nutrition does not exist … and therefore “completeness” is misleading.
Several companies claim to have done independent laboratory testing and verification of their nutritional composition but have not shared their data. One company, citing a "no animal testing" policy, refuses to run digestibility tests. NOT ONE OF THE COMPANIES provided details of their laboratory results or would verify the specific nutritional content of their diets. So if everyone says they're doing the proper tests, everything is good, right?
Dogs must be fed diets that are palatable, bioavailable, and that are nutritionally complete and balanced. Each life stage requires specific nutrients and essential amino acids (EAA) in order to maintain health. It is important to remember that dogs—all species actually—REQUIRE NUTRIENTS, NOT INGREDIENTS. The chart above shows AAFCOs minimal levels of EAA for adult dog maintenance. So as not to be misleading, please note that AAFCO publishes MINIMUM standards, NOT optimal recommendations. The two colored lines show the EAA profiles for a leading plant-based and a leading meat-based diet. How is it that two "radically" different diets can deliver almost identical EAA profiles? Lets have a look at the ingredient decks for both as well as a new entrant; "clean protein based" (for the record, the term "clean protein" is neither ALLOWED nor RECOGNIZED by AAFCO). The ingredients in red are common across all three. The ingredients underlined are artificial/synthetic ingredients. As you can see, all three diets use similar synthetic ingredients, which may be why they have similar nutrient profiles despite having different protein sources. Is extrusion the "great equalizer", rendering a similar output despite the input? A better question is this; Is it better for your dog to get ingredients like synthetic Choline Chloride or Choline that naturally occurs in plant and animal sources? Choline is a water-soluble compound and an essential nutrient. It is important in the synthesis and transport of lipids and it aids in the production of methionine. The answer comes down to which version a dog can more easily digest, making the nutrients readily available for absorption and usage (SPOILER ALERT: its NOT the synthetic versions).
According to Dr. Andrew Knight (2016), there is—at least in theory—no reason why a diet comprised entirely of artificial and synthetically-based ingredients cannot meet the AAFCO formulation requirements. While this is true, the resulting diet would not be optimal due to digestibility and bioavailability of the nutrients. Synthetic ingredients were first created as a way to replace the nutrients that were lost during the extrusion process. Vitamin loss due to extrusion varies from 4% on thiamin to 65% on Vitamin A. The extrusion process also causes a reduction of bioavailability (via binding to sugars) of amino acids such as lysine, arginine, cysteine, histidine and tryptophan. This happens to BOTH plant-based and meat-based diets that are made through extrusion (the "great equalizer" strikes again)!
COMPLETE & BALANCED?
P.G. Semp (2014) asked 174 dog owners to complete a questionnaire about their experience feeding a vegan/vegetarian diet. Animal participants were required to have eaten an exclusively vegan/vegetarian diet for at least six months; and to ensure dietary integrity, cats were required to have lived indoors only. Each interview was followed by a clinical examination and blood tests on 20 dogs that were randomly selected. The clinical examination included assessments of general appearance, body condition, skin and coat, lymph nodes, vital signs; cardiovascular, respiratory and digestive systems; and defecation. Hematological (complete blood count) and biochemical (liver, kidney, and pancreatic) parameters were assessed, as well as levels of magnesium, calcium, iron, total protein, folic acid, vitamin B12, and carnitine. A summation of the clinical examinations showed that for dogs, no significant differences were evident in any of the tested parameters, compared to the dogs fed a conventional meat-based diet.
Similar results were presented in 2009 (Brown et. al.). A study of 12 sprint-racing Siberian Huskies 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, which was replaced by maize gluten and soybean meal in the meat-free diet. The dogs were fed these diets for 16 weeks, which included 10 weeks of competitive racing. Health checks were conducted by a veterinarian blinded to the dietary regimens. All dogs were assessed as being in excellent physical condition, and none developed anaemia or other detectable health problems.
It appears that, at least in the short term, commercially available vegan/vegetarian diets are as efficacious as meat-based diets. The larger and more important question is the long term impact. At this point, no studies have been done to inform us of the risks and benefits of a lifetime of feeding vegan diets. What has been done is nutrient analytics to see if the diets are deficient in any area. In 2015, Kanakubo, Fascetti and Larsen showed that several commercial vegan diets were found to be deficient in energy (three diets), calorie (three diets) protein (one diet), and in potassium (three diets). Nutrient gaps were found in the amino acids methionine and cysteine, vitamin B12, and sodium. While energy and caloric deficiency is a labeling issue, long term deficiencies in potassium and B12 can lead to hypokalemia and anemia, respectively, in dogs. Symptoms of potassium and B12 deficiency include generalized muscle weakness, lack of appetite, lethargy, weight loss and confusion. In the event of a sodium deficiency, there is an increase of water in brain cells and the symptoms are usually neurological in nature. Dogs experiencing deficiencies in methionine and cysteine will see decreased food intake, weight loss and dermatitis. Of note, these are sulphur containing amino acids and the synthesis of cysteine accounts for half of the methionine requirement in a dog's diet. When cysteine is present in the diet, it lessens/spares the metabolic requirement of methionine. Cysteine is also a precursor to taurine in dogs. Deficiency symptoms can range from poor skin and coat health to taurine deficient cardiomyopathy.
While these deficiencies were found in commercially available diets, the prospect of a homemade diet being "complete & balanced" is dim. The Cummings School of Veterinary Medicine at Tufts University has stated that, "designing a meat-free food for dogs that contains all of the necessary nutrients for them to thrive is extremely difficult, even for a licensed veterinary nutritionist." While there are plenty of supplements available for homemade vegan diets, the quality and digestibility of the nutrients remains unknown and therefore the risk of creating imbalances and deficiencies is even greater. It is like making a cake; you can have the right components but without the proper know how and analytics, the quality of the finished product will vary greatly.
ANECDOTAL BENEFITS OF A VEGAN DIET
A growing body of anecdotal evidence suggests that dogs and cats can survive, and indeed thrive, on nutritionally-sound vegan/vegetarian diets. Benefits commonly reported include: decreased ectoparasites (fleas, ticks, lice and mites) and food intolerance reactions; improved coat condition; obesity reduction; regression in signs of arthritis; diabetes; cataracts; urogenital disease; and improved vitality. Amazing, right? So why are we (consumers and manufacturers) not insisting on randomized control trials (RCTs) to reduce biases and understand the effectiveness of vegan/vegetarian diets?
WHAT ABOUT DCM AND VEGAN DIETS?
Dilated cardiomyopathy (DCM) is a potentially fatal disease affecting about 2% of all dogs, appearing mostly in large breeds. A small percentage of these lack sufficient cardiac L-Carnitine, which can predispose them to this disease. The FDA is currently investigating an increase in reported cases due to diet (Nutritionally Mediated DCM). While some have attempted to link ingredients, no such causal relationship has been found. According to Ryan Yamka (board certified in companion animal nutrition by the American College of Animal Sciences and a fellow with the American College of Nutrition), DCM, "...likely has nothing to do with legumes at all and most likely has to do with actual nutrients, like levels of total dietary fiber, soluble fiber and resistant starch, cysteine, methionine and taurine, and their availability. Most dry kibble contains more than 35% carbohydrates, heat resistant starches and soluble fiber since they are needed for the processing of kibble." Considering that plant-based diets use many of the "suspect" ingredients, Dr Yamka's statement strengthens the need for manufacturers to properly formulate vegan/vegetarian diets and to be TRANSPARENT while doing so.
Feeding a Vegan/Vegetarian Diet is NOT the problem. Poor formulations, poor digestibility, nutrient deficiencies and lack of manufacturer transparency in the production of ALL pet food is the problem.
Interest in vegan/vegetarian companion animal diets will continue to grow. Vegan/Vegetarian diets show great promise, both anecdotally and in the short term! NOW is the time for studies to ascertain the nutritional adequacy of these diets and on the long term health benefits/implications for companion animals. Significantly greater resources need to be applied to understanding vegan/vegetarian diets than was put towards knowing the impact of grain-free diets. As pet owners, we should consider requesting specific details from manufacturers in regard to their inclusion rates and digestibility levels. If enough of us demand these things, companies would respond with better quality control standards, independent verification, and transparency! All of this would increase consumer confidence and the safety and quality of ALL companion animal diets, not just vegan/vegetarian. Regardless of what a manufacturer may tell you, sharing their amino acid test results does not divulge trade secrets! Be persistent; be an advocate; spend your money elsewhere if you don't get answers. If you choose to feed a vegan/vegetarian diet, you should monitor your pet's health with regular checks of bodyweight, activity level and overall demeanor. At an absolute minimum, veterinary visits should be done annually; biannually (or more frequently) if your pet has a health condition. As always, consult with your veterinarian before starting any significant dietary changes.
NO MORE GIMMICKS
If you are a manufacturer of pet food, you are accepting a great responsibility: the health and well being of a beloved animal and member of the family. Instead of seeking the PR limelight and creating marketing/advertising gimmicks with your food, share what REALLY matters to the well-being of the pet; your digestibility, amino acid and nutrient profiles? Again, it isn't about ingredients - its about nutrients. If you don't want to share your results, or worse yet, you don't know them, maybe you should've taken that left turn at Albuquerque!
At Guardian, we believe in "Pets Before Profit". We make freeze-dried foods that deliver quality nutrients. Our philosophy of "targeted nutrition" provides what is required for optimal health, nothing less. Regardless of your personal feeding philosophies, our goal is to make a better pet food that you can be confident in choosing to feed to your pet. Meat-based, plant-based or insect-based, our products will all be highly digestible and only use ingredients from nature (and when that is not possible, we will minimize the inclusion of synthetics). We will provide these foods in an easy to use, convenient form. We will be transparent and most importantly, we will always adhere to our founding principles of being...