What is a grain-free diet?
Grain free diets substitute ingredients such as wheat, corn, barley, and rice for other carbohydrates such as legumes, lentils, and potatoes. Many owners seek grain free diets when their dog suffers from food allergies. However, not only are food allergies extremely rare, but they typically are caused by a protein source such as chicken or beef (not grains). Recently, boutique and exotic diets often created by smaller food companies without certified veterinary nutritionists or veterinarians on staff have also been associated with cardiac abnormalities. We will group these diets together and consider them boutique, exotic, and grain-free diets (BEG).
Dogs are NOT wolves
It’s a common belief that dogs should be fed like their wolf ancestors, and this is a frequent marketing strategy for many BEG pet food companies. Wolves don’t eat grains in the wild so why should I feed them to my dog? Dogs were domesticated over 15,000 years ago for the purpose of herding, hunting, protection and eventually companionship. Canines are monogastric omnivores. Traditionally, in the wild canine species ate a carnivorous diet, however since the domestication of the dog they have adapted to digest and utilize plant-based nutrients. Dogs have more copies of the genes that produce the enzymes amylase and maltase than their wolf ancestors. These enzymes are present in the digestive system and help break down carbohydrates and starches. Research has shown that the enzyme amylase is 28 times more active in dogs compared to wolves. Additionally, dogs have a longer version of the enzyme maltase present in their digestive system. This longer version is also seen in other herbivores such as cows and rabbits. This means that dogs are five-fold more efficient at digesting starch, the chief nutrient in agriculture grains such as wheat and rice.
What is dilated cardiomyopathy (DCM)?
Dilated cardiomyopathy is a condition where the chambers of the heart are enlarged because the heart muscle is weakened and cannot pump properly. This results in difficulty pumping blood throughout the body and can result in fatigue and shortness of breath (among other symptoms). It can be caused by a variety of factors including genetics, taurine deficiency, infectious diseases, and most recently discovered, BEG diets.
What is taurine?
Taurine is a sulphur containing amino acid synthesized from methionine and cysteine in the liver and central nervous system. Taurine is essential for proper heart function. Because DCM was linked to taurine deficiency in cats, it was predicted that diet-associated DCM in dogs was also a result of taurine deficiency.
What does the literature say?
In 2021, the College of Veterinary Medicine at the University of Florida conducted an observational study examining echocardiograms, cardiac biomarkers, and whole blood and blood plasma taurine levels in dogs eating grain-free and grain inclusive diets. Overall, taurine levels were not depleted in dogs eating grain-free diets, however, they did express higher high-sensitivity cardiac troponin I (hs-cTnl), a cardiac biomarker that might indicate low-level cardiac injury. What does this mean? Dogs fed grain-free diets may have low-levels of heart injury.
In 2022, BMC Veterinary Research published an article comparing the outcomes of healthy Labrador Retrievers fed grain-free legume rich diets versus grain inclusive diets over 30 days to dogs with suspected dilated cardiomyopathy. Overall, Labradors fed the grain-free legume rich diets experienced reduced red blood cell (RBC) levels and hyperphosphatemia, results consistent with dogs with suspected DCM. What does this mean? Labradors fed grain-free diets had blood test results similar to dogs with suspected DCM.
The Journal of Veterinary Internal Medicine published an article in 2022 examining DCM in dogs eating non-traditional (NTD) or traditional diets (TD) and in dogs with subclinical cardiac abnormalities (SCA). Cardiac tests were performed on dogs with DCM and SCA on NTD diets prior to their diets being changed to TD. Cardiac biomarkers were reassessed at 3, 6, and 9 months, and revealed that dogs with previous DCM or SCA eating NTDs had small, but significant improvements in echocardiographic parameters after diet changes. What does this mean? Dogs with DCM or cardiac abnormalities being fed a grain-free diet can experience improvements in heart health following a switch to grain-inclusive diets.
What we don’t know
The literature available on diet-associated DCM is scarce and not indicative of an exact cause. It was initially thought that taurine deficiency was the main cause for DCM in dogs fed BEG diets, however, research indicates the cause to be multifactorial. In conclusion, BEG diets are correlated with heart related issues in dogs and more research is needed to determine the exact cause.
What to do if your dog is on a BEG diet?
Talk to your veterinarian.
Perform an echocardiogram to evaluate for the presence of DCM. Currently, this is the gold standard method of diagnosing DCM.
Consider switching to a grain inclusive diet.
Depending on the results of the echocardiogram, additional treatments may be recommended.
What is North Legacy Labradors feeding?
At North Legacy Labradors, we have always trusted in three main food brands for our dogs: Royal Canin (Eukanuba), Purina Pro Plan and Hills. These brands are backed by scientific research, feeding trials, and board-certified veterinary nutritionists. Thankfully, these three brands have not been associated with diet associated DCM. We realize that the issue surrounding BEG diets and DCM is multifactorial and it will likely take many years to undercover the root of the problem. Therefore, we will continue to feed our trusted food brands to our dogs that have always kept them happy and healthy. We encourage you to do the same until more information is available.
References
Adin, D., Freeman, L., Stepien, R., Rush, J. E., Tjostheim, S., Kellihan, H., Aherne, M., Vereb, M., & Goldberg, R. (2021). Effect of type of diet on blood and plasma taurine concentrations, cardiac biomarkers, and echocardiograms in 4 dog breeds. Journal of Veterinary Internal Medicine, 35(2), 771–779. https://doi.org/10.1111/jvim.16075
Bakke, A. M., Wood, J., Salt, C., Allaway, D., Gilham, M., Kuhlman, G., Bierer, T., Butterwick, R., & O’Flynn, C. (2022). Responses in randomised groups of healthy, adult Labrador Retrievers fed grain-free diets with high legume inclusion for 30 days display commonalities with dogs with suspected dilated cardiomyopathy. BMC Veterinary Research, 18(1). https://doi.org/10.1186/s12917-022-03264-x
Freeman, L., Rush, J., Adin, D., Weeks, K., Antoon, K., Brethel, S., Cunningham, S., Santos, L. D., Girens, R., Goldberg, R., Karlin, E., Lessard, D., Lopez, K., Rouben, C., Vereb, M., & Yang, V. (2022). Prospective study of dilated cardiomyopathy in dogs eating nontraditional or traditional diets and in dogs with subclinical cardiac abnormalities. Journal of Veterinary Internal Medicine, 36(2), 451–463. https://doi.org/10.1111/jvim.16397
Walker, A. L., DeFrancesco, T. C., Bonagura, J. D., Keene, B. W., Meurs, K. M., Tou, S. P., Kurtz, K., Aona, B., Barron, L., McManamey, A., Robertson, J., & Adin, D. B. (2022). Association of diet with clinical outcomes in dogs with dilated cardiomyopathy and Congestive Heart Failure. Journal of Veterinary Cardiology, 40, 99–109. https://doi.org/10.1016/j.jvc.2021.02.001
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