Concerns with Grain-Free Pet Food:

Updates on Diet-Associated Heart Disease in Dogs

Veterinary cardiologists and the FDA have been investigating a link between a canine heart disease called dilated cardiomyopathy (DCM) and certain pet foods that include legumes (peas, lentils, etc.) or potatoes as main ingredients. The ingredients of concern are commonly found in diets marketed as grain-free, but a link has also been found with other types of boutique and exotic ingredient diets.  We are alarmed because DCM is being seen in dog breeds that are not traditionally prone to it. 

What is dilated cardiomyopathy (DCM)?

DCM is a disease of heart muscle that leads to a large, flabby heart, which then causes fluid to accumulate in the chest and abdomen. DCM causes symptoms like reduced energy, coughing, difficulty breathing, collapse, and death. In the past, DCM generally only affected certain breeds of dogs with a suspected inherited genetic link (Dobermans, Boxers, Great Danes, Newfoundlands, Irish Wolfhounds, Saint Bernards , and Cocker Spaniels).  DCM is now being seen in other breeds, and these dogs were reported to have been fed newer Boutique, Exotic Ingredient, or Grain-Free (“BEG”) diets. Some of these patients have been found to have low blood taurine levels, which is a proven cause of DCM. Unlike traditional DCM patients, heart function in dogs with diet-associated DCM may improve with veterinary care and diet change.

DCM was common in cats in the 1980s, until an association was made with taurine deficiency. Feline DCM could be reversed with taurine supplementation, and the overall frequency was drastically reduced when the requirement for taurine in cat food was increased. Perhaps a similar scenario will play out for our canine patients.

Which pet foods are involved?

Grain-free diets aren’t the only source of diet-associated DCM; foods from boutique companies and those with exotic ingredients have also been found to cause the same heart problems. Veterinary nutritionists suspect the legumes and potatoes used instead of traditional grains or other exotic ingredients may be involved. A lack of qualified nutritional expertise and quality controls is another potential source of issues with many of these diets.

The FDA recommends reviewing the pet food’s ingredient list to see whether legumes (peas, beans, lentils, chickpeas, soybeans, peanuts, pea protein, pea starch, pea fiber) or potatoes (including sweet potatoes and red potatoes) are listed as a main ingredient (ie. listed before vitamins or minerals). High levels are common in grain-free foods but may also appear in other diets.

June 2019 updates: the FDA published a list of brands most commonly named in reported cases. Over 90% were labelled as “grain-free” and 93% contained lentils and/or peas. A much smaller number of listed foods (42%) contained potatoes.

Cardiologists have defined 3 types of DCM in dogs:

  1. Breed-specific DCM: this is the traditional, inherited type that happens in certain large and giant breed dogs. It is develops unrelated to diet.
  1. Diet-associated DCM with taurine deficiency:this type is not related to breed/genetics. A low blood taurine level is found. Fortunately, nearly all these patients have improved with taurine supplementation and diet change.
  1. Diet-associated DCM without taurine deficiency: this type is caused by a different but currently unknown dietary factor(s) in BEG diets. Potential causes are a nutrient deficiency, impaired absorption of a nutrient, or even a heart toxin. Some of these dogs improve with diet change.

Additionally, some dogs with breed-specific DCM eat BEG diets, and there are many dogs without heart disease eating BEG diets.

What is taurine and how do taurine deficiencies develop?

Taurine is an amino acid (component of protein). The reason some dogs develop taurine deficiency is not completely understood at this time, but it is suspected to be related to reduced synthesis of taurine. Golden retrievers may be especially predisposed to developing taurine deficiencies.

What are BEG diets, and why are veterinarians so concerned about them?

Cardiologists have listed 23 different BEG diets fed to dogs diagnosed with diet-associated DCM. They fall into these categories:

Boutique brands, raw, or home-cooked diets have been found to be more prone to nutritional imbalances, which may be related to a lack of nutritional expertise (ie. not employing veterinary nutritionists or conducting pet nutrition research) and/or lack of adequate quality controls. Deficiencies are more likely to occur with lax quality control standards or lack of feeding trials and proven digestibility of ingredients.

Exotic ingredients (like kangaroo, duck, buffalo, salmon, lamb, bison, venison, lentils, peas, fava beans, tapioca, barley, and chickpeas) have become mainstream in pet foods, but these non-traditional ingredients make it much trickier to ensure nutritional balance. Their nutrient profiles, digestibility, and interactions with other ingredients less understood as traditional ingredients. Although they are often marketed as being more natural or healthier, there are actually no proven benefits with exotic ingredients. Less understanding of these ingredients means pet food companies using them need better quality controls, testing, and supplier audits; but these standards are unfortunately not commonly seen with the boutique brands using them. Veterinary nutrition specialists actually recommend “ignoring the marketing and avoiding diets with exotic meats…They aren’t helping your pet, but they are likely hurting your wallet!”

Grain-free diets may be a problem because they tend to utilize legumes and potatoes to replace traditional grains, and these ingredients have been the primary concerns with diet-associated DCM.

The underlying problem could also be accidental inclusion of a heart toxin (ie. a heavy metal contaminant, pesticide chemical sprayed on an ingredient, or a natural component that is toxic in large amounts). The cause could even turn out to be incredibly complicated, like an interaction between a specific dietary factor and gut microbes. It is also possible this could be a false association altogether, though this is unlikely due to many patients improving with diet change and taurine supplementation.

Many people (and many pet food companies) completely underestimate the complexities of the pet food manufacturing process. Although minimum and maximum nutrient standards are established by the Association of American Feed Control Officials (AAFCO), the effects of digestibility and processing, and the effects ingredients have on each other must be well understood and accounted for—but this is not always the case, especially with BEG diets. Acceptable quality control requires extensive, ongoing testing, which is often not in place. Errors are easy, especially when incorporating exotic ingredients that are not as well understood as standard ingredients. For example, the body uses taurine differently from a lamb-based diet than from a chicken-based food, and taurine usage is also affected by the types and amounts of fiber. These subtle nuances mean it is critical for pet food companies to invest in qualified nutrition specialist employees, ongoing product research/development, and strict quality controls; again, this is unfortunately not the case with many companies.

What are the current recommendations?

  1. The FDA recommends evaluating the main ingredients of dog food (any ingredients listed before vitamins and minerals) to check for legumes or potatoes, which seem to be related to diet-associated DCM.
  1. Veterinary nutritionists recommend owners reconsider feeding BEG diets to dogs until the cause(s) of diet-related DCM
    have been worked out, and they recommend feeding commercial pet foods made by an established manufacturer that contains common ingredients, including grains. If an individual pet must have a home-prepared diet due to medical conditions or strong family preference, then a veterinary nutritionist should be involved ( or are good options).
  2. Veterinary cardiologists recommend that dogs diagnosed with DCM be screened for low taurine levels. All other dogs in the household that are eating the same diet should also be screened for DCM.
  1. Dogs with possible diet-associated DCM should be switched to a diet made by a well-established manufacturer with standard ingredients (beef, chicken, rice, corn, wheat) and given a taurine supplement.

What pet foods are best?

Unfortunately, advertising by the pet food industry has exceeded nutritional science, so it has become challenging for pet owners to wade through the myths and misinformation to make healthy pet food choices. Having thousands of pet food options makes it even more difficult to sort out the great foods from the ones that only have great advertising. This growing issue of diet-associated DCM highlights the urgent need to return to a research and quality control based approach to pet nutrition instead of the current reliance on fads, myths, and consumer marketing strategies.

Talking to your veterinarian is important to discuss your pet’s individual nutritional needs, life stage, body condition, activity level, and any medical conditions. When assessing a pet food label, remember the ingredient list doesn’t tell us anything about quality or absorption of the ingredients or if they are in correct proportions. The ingredient list is primarily used by many companies for marketing. Many online ratings websites fall into the same trap of ranking foods by ingredients, opinions, or myths rather than sound nutritional knowledge, so don’t waste time with them either!

One useful part of the package label is the nutritional adequacy statement (“AAFCO Statement”). However, according to veterinary nutrition specialists, the most important  information is actually the name of the company, which truly most determines the quality and nutritional expertise going into the food. Cost or level of marketing really don’t indicate which companies are best.

Although picking the best pet food is made difficult by scary nutrition myths and excellent marketing, here are the most important questions to research:

  1. Does the company employ AT LEAST one FULL-TIME qualified nutritionist? This means a PhD in animal nutrition and/or board-certification by the American College of Veterinary Nutrition or European College of Comparative Nutrition. This does not include veterinary technicians or general practice veterinarians like me, and only consulting occasionally with a qualified nutritionist isn’t adequate either. Lack of full-time employees with true expertise in nutrition is a huge red flag that the company does not actually prioritize nutrition.
  1. Does the company own the plant(s) where their food is manufactured? Many small/boutique companies do not, which limits the control they have over quality.
  2. What quality control measures do they practice?These vary widely and are often ignored, but are critical to producing safe, consistent, healthy food. Advertising that your food is highest quality does not mean it is true. A label statement that the food is “complete and balanced” is not always true either (and outside studies have found deficiencies in many of the foods that don’t meet this list of standards). Good examples of quality controls include Certification of Procedures by the Global Food Safety Initiative, Hazard Analysis and Critical Control Points, or American Feeding Industry Association; testing ingredients and end products for nutrient content, pathogens, aflatoxins; materials risk assessments; and supplier audits. Lack of decent quality controls is common but should make you extremely cautious about choosing their foods.
  1. Is the food proven with Association of American Feed Control Officials (AAFCO) FEEDING TRIALS?This information should be listed on the package label. If the company does not do AAFCO feeding trials, then they should at least prove they meet AAFCO nutrient profiles through analysis of the FINAL product (not just predicting they are good enough based on the recipe only)–you’ll have to call the company to ask for this information.
  1. Does the company conduct any research? Is it published in peer-reviewed journals? Lack of contribution to furthering our knowledge of pet nutrition is another red flag.
  1. Can the company provide you with the specific amount of any nutrient, like sodium or calcium?They should be able to give you the exact amount, not just the minimum or maximum (which are basically useless). This number should ideally be reported on an energy basis (grams per 100 kilocalories or grams per 1,000 kilocalories). If the company does not know these details about their foods, you should not trust their products.
  1. Can the company provide you with number of calories for any of their foods on any basis(ie. per cup, per can, or per kilogram)? If they do not know, you should be very skeptical of their final product.
  1. Does the company bash other pet food manufacturers, especially using pet food myths? If so, you should question how reputable they truly are.