Recent reports discussing the potential relationship between grain-free pet foods and Dilated Cardiomyopathy (DCM) have given pet owners and veterinarians alike a cause for concern. Pet owners and the veterinary community have been led to believe that some pet foods – particularly grain-free pet foods – are causing heart disease in dogs. However, the data buried within the FDA report tells a different story, one that is complex, without evidence showing a causative relationship between grain-free diets and heart disease. Multiple factors surround this issue – and none of them are simple. The fact is, little research and data are available surrounding this potential relationship, and some within the industry have failed to recognize a greater problem. DCM is just one of many concerns pet owners have to face, along with cancer, diabetes, kidney disease, and allergies to name a few. For owners and veterinarians concerned about grain-inclusive or grain free, they are likely concerned about the wrong risk; instead, the concern should be centered around the significant gaps in the field of animal nutrition. These gaps include but are not limited to formulation guidelines that are narrowly researched, outdated research, and foods full of toxic chemicals and byproducts of food processing. The DCM events have highlighted these gaps and the complexity of the field of nutrition, for those simplifying it to a set of ingredients are doing pets & the scientific community a disservice. In this review, we examine the scientific evidence that highlights the complexity of nutrition & DCM.
Timeline of FDA Investigation & Reports
- In June of 2018, Lisa Freeman, a board-certified veterinary nutritionist from Tufts University published a blog titled “A broken heart: Risk of heart disease in boutique or grain-free diets and exotic ingredients.” This blog warned pet owners and veterinarians that ‘BEG’ (boutique, exotic, grain free) diets were causing heart disease in dogs.
- July 2018, FDA announces an investigation into the potential association of canine DCM and grain-free foods. On the heels of this press release, the New York Times published an article creating a media storm.
- In November of 2018, Dr. Freeman published another blog on the Tuft’s Petfoodology website titled, “It’s Not Just Grain Free: An Update on Diet-Associated Dilated Cardiomyopathy.” This reiterated their warning about BEG diets and their association with DCM. This article also was circulated as if it was peer-reviewed when it indeed was another opinion piece.
- In December of 2018 Freeman et. al. authored a commentary article in JAVMA titled, “Diet-associated dilated cardiomyopathy in dogs: what do we know?” It’s important to note that this paper also was not peer-reviewed, and the AVMA (American Veterinary Medical Association) disseminated it as gospel. This is unfortunate considering 80% of veterinarians believe or look at AVMA as a source of truth even if a commentary article does not contain true or accurate scientific content.
- Also, in December 2018 there was a paper published in PLOS ONE by Kaplan et al. titled, “Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets.” The major complicating variable (and there were many) was that golden retrievers are well known to have a genetic predisposition to DCM, as well as have a higher requirement for taurine. Simply, this means that this study cannot be easily applied to the entire canine population.
- February of 2019 – The FDA published an update showing a few hundred reported cases in the prior 7 months. It also revealed that the majority of pets were eating dry food, were golden retrievers, and that ingredients like peas, sweet potatoes, lentils, chickpeas, and potatoes were potentially associated with DCM. They also revealed that all diets implicated did appear to be nutritionally adequate based on testing.
- June 2019 – the FDA released another update naming the most common 16 brands of dog food reported alongside DCM cases. This report along with the accompanying graphs was taken out of context leading the general public and veterinary community to believe that they had made a connection to specific brands and disease when in fact the FDA report states that they believe it to be a complex scientific issue.
- In May of 2020 a paper titled, “Development of plasma and whole blood taurine reference ranges and identification of dietary features associated with taurine deficiency and dilated cardiomyopathy in golden retrievers: A prospective, observational study” was published in PLOS ONE. The article contained multiple inaccuracies, failure to disclose conflicts of interest, and issues that are currently being reviewed. In the meantime, the journal has issued an expression of concern. Regardless, this paper also taken out of context has led the public and veterinary community to believe that the issue is a simple relation to ingredients instead of the complex issue that it is.
- In June of 2020, an article published in Journal of Animal Science highlighted just how complex DCM and various nutritional and non-nutritional etiologies are. The authors state, “based on this review of the current literature, there is no definitive relationship between these implicated diet characteristics and DCM.” While the public and veterinary associated communities made several further conclusions upon the release of the article, it is important to realize that this paper largely identifies the numerous knowledge gaps within the field of canine nutrition rather than drawing concrete conclusions. While no link between ‘BEG’ (boutique, exotic, grain free) pet foods were found, this does not mean that nutrition and other considerations are not at play.1 You can read our full summary of that article here.
What is DCM?
Dilated Cardiomyopathy (DCM) is defined as a condition where the heart becomes enlarged and is unable to adequately pump blood. DCM can include mechanical dysfunction and/or electrical dysfunction which leads to sudden collapse and death.2 As DCM progresses signs include lethargy, loss of appetite, shallow breathing, intolerance to exercise, and shortness of breath. This disease is known to occur in dogs and cats, at varying levels of severity and has multiple causes.1,3
Further complicating matters DCM has causation that is likely multivariable such as genetics, environmental, nutritional, infections, heavy metal exposure, dysbiosis, and even other unknown causes1,3.
A large issue is that the true prevalence of DCM in canines is unknown. One of the reasons is that there is no central reporting agency that tracks diseases for companion animals. Literature estimates the prevalence of DCM in dogs, prior to grain-free foods being widely available, to be 0.5 to 1.1% of the overall dog population.4 Based on the current data it would appear that the prevalence of DCM is still within the same parameters even with increased reports made to the FDA. That said, it is unclear if cases have been underreported, and continue to be underreported or if there is a significant spike in cases as a result of these diets, or multiple other variables.
DCM is not a ‘new’ concern for dogs or cats. In fact, it has been around for a long time. In the 1970’s -1980’s, DCM was prevalent in cats and it was eventually determined that this was due to low concentrations of taurine and animal protein within the commercialized foods.5 Pet food companies responded by adding taurine through supplementation and additional meat protein which has since seemed to remedy this issue for cats.6 Since dogs and cats are nutritionally different it is unlikely that adding taurine to any canine diet will be sufficient to solve the current issue in dogs, especially since diet-related canine DCM is likely far more complex. Further complicating matters, the only definitive diagnosis for DCM is an echocardiogram, which the majority of “cases” highlighted within the FDA report lack. Other methods of screening for potential cardiac disease are whole blood taurine, plasma taurine, auscultation, and chest x-ray, although these methods are not reliable in diagnosing DCM.
Genetics at Play
We know that certain breeds are genetically predisposed to DCM and those include (but are not limited to) Doberman Pinschers, Boxers, Great Danes, Labrador Retrievers, St. Bernards, Irish Wolfhounds, Golden Retrievers, Newfoundlands, English, and American Cocker Spaniels5,7. There is no cure for genetic DCM, and conventional treatment provides limited relief for a generally short period of time.8
Not Just Grain Free
Not all dogs diagnosed with DCM were consuming a grain free diet.9. Most dogs were also eating dry food, which raises the question grain free not being a problem per se – instead showing evidence of a knowledge gap in the formulation.9 As the report notes, some improved after a diet change from one grain-free diet to another, and this along with differences identified between dogs fed various grain-free diets, suggests that DCM is not necessarily tied to the grain-free status of the diet.2,10 In addition, many dogs diagnosed with DCM were initially thought to be taurine-deficient, and we’ve since learned that this problem is far more complex than the presence or digestibility of taurine within dry pet food. We’re now realizing the presence of significant knowledge gaps regarding small animal nutrition.
Context: Few Pets are Healthy
In examining the whole picture, we know that dogs and cats are not “healthy” – a reality that most of us either ignore or don’t believe to be true. Common problems like skin conditions, “dog smell”, and GI issues are not – and should not be considered healthy; even though we’ve come to accept them as normal. Some of the causality behind “common” problems is that our pets have been, and still are, subject to many detrimental variables over generations and the consequences of such have impacted the overall wellbeing and susceptibility of varying types of disease. These variables include but are not limited to: toxins and pollution in the air, water, soil, and food supply, overuse of antibiotics and other medication, over vaccination, static diets, poor breeding practices, poor nutrition, lack of exercise, and radiation. Some, or more likely, each of these factors may have contributed to our pet’s susceptibility to a variety of diseases, including DCM. In fact, obesity, diabetes, and other issues have known relationships to DCM.11 All factors that complicate the scientific investigation.
Understanding Risk Factors
For the sake of context, the good news is that just because an individual is “predisposed” to a particular disease does not mean that they are going to “develop” that disease as the expression of a “bad gene” can be altered by a healthful diet and limiting exposure to toxins and stress.12 Let’s imagine for a second that an individual was predisposed to any type of heart disease, but they took care of themselves by consuming a diet consisting of fresh foods, including antioxidants along with moderate fat, and sodium, avoided excess use of vaccinations, limited unnecessary medications, consumed clean water and exercised to maintain strong cardiac function. These individuals most likely have a lesser chance of developing heart disease. The point is that multiple variables influence the expression of disease in any human or animal.
Nutritional Knowledge Gap
Pet food formulation comes from generalized minimal recommendations by the Association of American Feed Control Officials (AAFCO) and the National Research Council (NRC). It’s clear that these minimal benchmarks are not complete with adequate scientific evidence. For example, we do not have optimal levels for many nutrients and do not account for breed-specific requirements in most cases. These minimum nutrient recommendations have been established with research on Beagles as a proxy for all canines regardless of size or breed.2 These same recommendations also place pregnant bitches in the same category as growing animals – even though we know that nutritional requirements are different. Additionally, recommendations made by AAFCO correspond to a total nutrient content within the formulation and do not consider the true digestibility of ingredients leading to the potential of a variety of nutrient deficiencies across multiple breeds.13
Not All Diets Metabolized the Same
Some within the veterinary community have illogically lumped home-cooked, canned and raw diets into the “grain free” category, however, per the FDA report, the vast majority of DCM cases that were reported were for dogs consuming dry foods – not “grain-free” raw or “grain-free” cans, causing unnecessary panic at the expense of pet owners canned and raw foods. These diets are entirely different in formulation, composition, and differ in the way they are metabolized in comparison to dry diets. Fresh and unprocessed diets, like raw, will have abundant taurine and natural nutrients which may limit risks of malabsorption and nutrient deficiencies that are common in kibble and other processed diets. Oversimplifying this issue to “grain-free” raw, canned, and home-cooked diets is irresponsible and likely causing more harm than good.
Disproportionate Levels of Macronutrients & Micronutrient Deficiency
DCM aside, all grain-in and grain-free dry foods have a carbohydrate content of at least 30%, most being significantly higher. This can be a problem for several reasons that most haven’t recognized:
- Ingredients such as potatoes, peas, and other legumes and pulses have been used in grain-inclusive and grain-free dog food for nearly 25 years to provide dietary fiber and protein.14 Use of these ingredients at higher than 15% inclusion on a dry matter basis can decrease crude protein digestibility. Since some foods on the market have greater than 40%, and even up to 60%, inclusion could facilitate a higher risk of nutritional deficiencies, especially if the final product is not validated.2 This can also yield an inadequate amount of animal protein which may lead to an imbalance or not enough of various nutrients – one of which can be taurine, and too little taurine (taurine deficiency) can result in DCM.
- Some plant-based proteins, like pea or potato protein, can cause malabsorption and inflammatory conditions in humans.15 While insufficient research is available to suggest the same in pets, it is certainly a reasonable theory to explore. More institutions are exploring the similarities in humans and canines and while some still refute these similarities, the stark similarities in types and rates of disease are intriguing.16–18 Logically, these similarities are not surprising considering humans eat a highly-processed diet full of chemicals, lack exercise, overuse medication, and live exposed to environmental toxins and pollution, just like pets.
- The recent article by McCauley et al. highlighted the various nutritional considerations that may influence dietary DCM including choline, methionine, cysteine, taurine, carnitine, thiamine, copper, vitamin E, selenium among others.1
Before assigning blame to a particular ingredient, set of ingredients, or formulation it is prudent to first identify knowledge gaps – especially before establishing any causation to a particular disease. Further investigation into these inclusion percentages and relationship to canine health and risk factors is needed to understand these relationships. We cannot allow the industry to tunnel vision focus in the way that it has, as it will not yield useful results or a better understanding of the problem at hand.
Why Grain Free?
The pet food industry’s switch to grain free was not fueled by a problem with the grains themselves or grain allergies like most believe. In 2007, the largest pet food recalls in history was due to melamine and cyanuric acid contamination of wheat and rice ingredients coming from China. Also absent from the discussion on grain consumption for pets – and people – is the contamination of grains with herbicides, pesticides, mycotoxins, and fertilizers. Numerous peer-reviewed articles are detailing the disruption that many of these contaminants have on normal gut bacteria function. These are the largest reasons more animals and humans are becoming increasingly intolerant to grain and grain products.19,20 We are also learning that disruption of vital gut bacteria balance can have devastating effects on the health of the host including diabetes, obesity, autoimmune disease, cancers, GI issues, and even DCM.21–23 Said simply, the contamination of grains in pet food is likely why many pets experienced improvement of various symptoms with the change from grain-inclusive to grain-free.
Pet Food Processing & Chemical Factors to Consider
All kibble is heated to high temps which creates a chemical change. A Maillard Reaction Product (MRP) is the name for a series of reactions that is the product of sugar (carbohydrate) and protein when heated. These are also known as AGE’s or Advanced Glycated End Products. MRP’s are responsible for nutrient loss and associated with diseases like diabetes, cardiovascular disease, kidney disease, loss of cognitive function, allergies, periodontal disease, and chronic inflammation.24–29 This can mean things like arthritis, skin, and ear issues, an old injury that keeps resurfacing, bloating, IBS, etc. In addition, there is a large amount of research to suggest that they are carcinogenic and accelerate aging.29,30
Since we know so little about animal nutrition is it possible that much of the disease we’re seeing – including DCM has at least something to do with the MRP’s that are in pet food? Possibly.
The considerations surrounding DCM challenges are extremely complicated, with many unknowns. It will likely be many years before any formal answers are reached. Currently, there are no formal dietary recommendations for pet owners from the FDA as of the latest report. If your dog is in a risk group (breed, genetic, or other underlying condition) it is best to seek advice from your veterinarian on the health status of your pet.
Our canines are largely suffering from man-made diseases and conditions such as obesity, type II diabetes, and nutritional deficiency – among others. Most of these can be linked back to feeding low-moisture, high soluble carbohydrate, low meat protein, and ultra-processed dry food with high levels of contaminants. While there is a knowledge gap in the nutrition of both ultra-processed and raw, one cannot deny the association between ultra-processed foods and disease prevalence and progression.
It is imperative to understand and practice methods that recognize each animal as different, having unique needs. Not any one diet is complete – and no feeding regimen will be successful for all pets and this very practice is what has been detrimental to our pets and brought us to this point. As always, all diet changes and additions should always be introduced slowly and carefully. It is always helpful to keep a food journal that can help experts determine potential foods or feeding patterns that may be problematic.
*This article is for informational purposes only. It is not meant to provide medical advice or replace the advice of a qualified veterinarian. If you think your pet has DCM, or any medical condition please seek the advice of a qualified veterinarian.
About the Author: Nicole Cammack
Nicci is the owner of national award-winning NorthPoint Pets & Company and Undogmatic Inc, in Connecticut. Her undergraduate and graduate education includes biology, chemistry, business, and nutrition. She has worked in the pharmaceutical industry on multiple R&D projects and has had the privilege to learn from leading international figures in the human and pet health industry. She regularly lectures at national conferences, including federal, state, and municipal K9 events. Her current research involves identifying pathogenic risk factors and transmission among raw fed pets through a comprehensive worldwide survey.
- McCauley SR, Clark SD, Quest BW, Streeter RM, Oxford EM. Review of canine dilated cardiomyopathy in the wake of diet-associated concerns. J Anim Sci. 2020;98(6):skaa155. doi:10.1093/jas/skaa155
- Mansilla WD, Marinangeli CPF, Ekenstedt KJ, et al. Special topic: The association between pulse ingredients and canine dilated cardiomyopathy: addressing the knowledge gaps before establishing causation. J Anim Sci. 2019;97(3):983-997. doi:10.1093/jas/sky488
- Canine Dilated Cardiomyopathy (DCM). Cornell University College of Veterinary Medicine. Published December 13, 2017. Accessed May 15, 2019. https://www.vet.cornell.edu/hospitals/companion-animal-hospital/cardiology/canine-dilated-cardiomyopathy-dcm
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- Pion PD, Kittleson MD, Thomas WP, Skiles ML, Rogers QR. Clinical findings in cats with dilated cardiomyopathy and relationship of findings to taurine deficiency. J Am Vet Med Assoc. 1992;201(2):267-274.
- DCM: add taurine to grain-free dog foods, say scientists | PetfoodIndustry.com. Accessed May 15, 2019. https://www.petfoodindustry.com/articles/8162-dcm-add-taurine-to-grain-free-dog-foods-say-scientists?v=preview
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- Medicine C for V. FDA Investigation into Potential Link between Certain Diets and Canine Dilated Cardiomyopathy. FDA. Published online June 27, 2019. Accessed June 29, 2019. https://www.fda.gov/animal-veterinary/news-events/fda-investigation-potential-link-between-certain-diets-and-canine-dilated-cardiomyopathy
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