Mass social media hysteria has ensued as reports of grain-free dog foods causing heart failure have filtered down from the Food and Drug Administration (FDA). There is a lot of confusion and hear-say surrounding this issue therefore I wanted to provide some clarification for my clients (and anyone else who happens to stumble across this post).
Firstly, it is important to understand the difference between two terms frequently used in regards to medical studies - causation and correlation.
Correlation has to do with two things that change concurrently, but are not necessarily related. For instance, murder rates tend to spike when ice cream sales go up...however we all know that buying ice cream does not turn you into a killer (unless they run out of your favorite flavor).
Causation, on the other hand, refers to something that time and time again across multiple well-run studies has been show to CAUSE something else (for example, cigarette smoking causes lung cancer).
It is VERY hard to prove causality. Multiple high quality (double blind placebo controlled) studies usually across multiple years (sometimes decades) need to be performed and all other factors that may play into the apparent cause-and-effect need to be considered.
With regards to the grain-free dog food, we are experiencing the very first ripples of an issue that will probably extend into the next couple of decades before it all gets figured out. Here’s what we do know:
In July 2018, the FDA began investigating reports of a particular kind of heart disease (Dilated Cardiomyopathy) in dogs eating certain pet foods. Many of the case reports included breeds of dogs not previously known to have a genetic predisposition for DCM. Many of the foods were labeled “grain-free” and contained high levels of peas, lentils, other legumes, and/or potatoes in various forms (whole, flour, protein, etc.). From the FDA: “Based on the data collected and analyzed thus far, the agency believes that the potential association between diet and DCM in dogs is a complex scientific issue that may involve multiple factors.”
There do seem to be some breeds more affected than others.
Other breeds with more than one reported case include: Afghan Hound, Australian Cattle Dog, Beagle, Belgian Tervueren, Border Collie, Boston Terrier, Bull Terrier, Chihuahua, Dalmatian, English Cocker Spaniel, English Springer Spaniel, Flat-coated Retriever, French Bulldog, Gordon Setter, Hound (unspecified), Irish Setter, Irish Soft-Coated Wheaten Terrier, Jack Russel Terrier, Maltese, Miniature Schnauzer, Old English Sheepdog, Pomeranian, Portuguese Water Dog, Pug, Retriever (unspecified), Rhodesian Ridgeback, Rottweiler, Rough-haired Collie, Saluki, Samoyed, Schnauzer (unspecified), Shepherd (unspecified), Staffordshire Bull Terrier, Standard Long-haired Dachschund, Vizsla, Whippet, and Yorkshire Terrier.
Past research has revealed that Golden Retrievers in particular may have a genetic predisposition to taurine deficiency. This combined with certain diets may make them even more susceptible to DCM.
The vast majority of the dogs affected were on commercialized dry dog kibble.
Out of personal interest I further investigated the 9 accounts of dogs on raw diets who reported DCM. Three of the cases were feeding Nature’s Variety Instinct either Raw Boost or Limited Ingredient. All of these formulas contain peas, chickpeas, or pea protein within the first four ingredients. Two were feeding Nature’s Variety Instinct Raw which contains sweet potato as the sixth ingredient. One case fed Rawz Meal Free Dry Food Limited Recipe Wild Salmon which contains dried peas, pea starch, and tapioca starch within the first nine ingredients (it also contained a few other starchy components). One case was feeding a homemade raw diet so hard to know exactly what was being fed. Traditionally it is hard to balance a diet by yourself; possibly this case had a genetic component as well. The other two cases were feeding NRG Original Free Range Chicken Dehydrated Raw food and Primal Raw, respectively. As neither of these two foods contain peas or lentils, I suspect a genetic component or other factors in these two cases (NRG contained oats as the second ingredient which although I am not thrilled about, it has not been linked to DCM).
Interestingly, one case was switched TO a raw diet and taurine supplementation after being diagnosed with DCM and improved both clinically and on echocardiography.
There are 16 dog food brands that the FDA has reported as most commonly named in association with these DCM cases.
More than 90% of the diets fed were labeled “grain-free” and 93% contained peas and/or lentils.
No one animal protein source was predominant and product testing by the FDA did not reveal any abnormalities in mineral, metal, or amino acid levels in the diets (calcium, magnesium, phosphorus, iron, cobalt, copper, zinc, selenium, iodine, taurine, cysteine, and methionine).
So, what conclusions can we draw from this information? Certainly if we are currently feeding one of the 16 diets listed above, or another diet that is high in peas or lentils, we would want to re-evaluate and either supplement or transition to a more biologically-appropriate diet. If you are one of my clients, you have probably already heard my spiel about dry dog kibble and how it is nutritionally devoid and biologically inappropriate. Supplementing can be as easy as adding one can of sardines (packed in water, no salt added) per 25 pounds of body weight per week to your dog’s diet. This will provide a whopping punch of taurine and possibly counteract any negative effects of the current diet. I would also recommend that ALL dogs receive Standard Process Canine Whole Body Support to address any taurine or other nutritional deficiencies in their diets.
Since there does seem to be a genetic component, if you own one of the breeds listed above AND feed one of these diets, I would highly recommend following the four-step process in this open letter to pet parents written by Dr. Stern, a current researcher into the DCM-Diet issue, which starts with a veterinary exam.
In summary, there is still a LOT we do not know about the connection between these foods and DCM in dogs. Certainly peas and/or lentils seem to play a role. A current theory is that these and other carbohydrates react with taurine during the extrusion process (called the Maillard reaction) and deplete the digestible amount of taurine in the food. Another source theorizes that high dietary fiber from peas, lentils, and other sources negatively affect gut health and thus diminish the amount of taurine the gut can absorb from the diet (called bile acid binding). Whatever the cause, it once again seems to show that natural, biologically appropriate food that is minimally processed offers our pets the best chance at optimal well-being.
Food and Drug Administration 2019, “FDA Investigation into Potential Link between Certain Diets and Canine Dilated Cardiomyopathy”, U.S. Food and Drug Administration, accessed 25 July 2019, <https://www.fda.gov/animal-veterinary/news-events/fda-investigation-potential-link-between-certain-diets-and-canine-dilated-cardiomyopathy>.
Food and Drug Administration 2019, “Dilated Cardiomyopathy in Dogs & Cats: Complaints Submitted to FDA-CVM January 1, 2014 - April 30, 2019”, U.S. Food and Drug Administration, accessed 25 July 2019, <https://www.fda.gov/media/128303/download>.