FDA will not provide updates on DCM in dogs until meaningful science is provided: Have we learned anything thus far?

On December 23, 2022, the Food and Drug Administration (FDA) provided an update into its investigation into what it calls non-hereditary canine dilated cardiomyopathy (DCM):

“FDA does not intend to release further public updates until there is meaningful new scientific information to share. FDA has followed up on a subset of these reports, but is unable to investigate every report to verify or confirm the reported information. While adverse event numbers can be a potential signal of an issue with an FDA regulated product, by themselves, they do not supply sufficient data to establish a causal relationship with reported product(s). FDA continues to encourage research and collaboration by academia, veterinarians, and industry.” 

You may recall that the FDA made a big announcement that it was seeing an association of non-hereditary DCM and legumes like peas, of which the latter is added to grain-free kibble as a binder. Think of it as replacing flour in chocolate chip cookies. Flour in chocolate chip cookies binds the sugar, butter and the rest of the ingredients prior to baking. 

Then, the FDA implicated 16 brands that were most frequently mentioned by companion pet parents or attending veterinarians. Bear in mind, the FDA listed brands – not individual products – and some of the brands make grain-inclusive dog food formulations as well as grain-free. 

This is what the FDA states in its Q&A section now:

“8. Is this an issue with only grain-free diets or diets containing legumes or pulses?

No. FDA has received reports of non-hereditary DCM associated with both grain-free and grain-containing diets. Most of the diets associated with reports of non-hereditary DCM have non-soy legumes and pulses (e.g., peas, lentils, etc.) high in their ingredient lists. However, it is important to note that legumes and pulses have been used in pet foods for many years, with no evidence to indicate they are inherently dangerous. CVM’s data show that pulse ingredients are likely used in many ‘grain-free’ diets in greater proportion than in most grain-containing formulas.”

Confusion

If you have been following this like we have, you might think this turnabout is abrupt. 

We point to a forum hosted by Kansas State University in September 2020. The FDA reported following 150 cases – which is a good sample size – of the approximately 1,100 received by that time. Bear in mind, the agency only follows cases at this stage of an investigation and does not intervene with recommended individual treatment plans. The FDA also wanted two echocardiograms for inclusion. All of that is fine. 

As an aside, some are outraged that the FDA did not follow-up on the 1,382 reported cases that are available for the public to read. Anyone could report – companion pet parents and veterinarians alike. While the reports are heart wrenching and we can feel the sorrow through the words of companion pet parents, many reports did not provide enough information for the FDA to use. 

We find it troubling that the 90% of the dogs included in the sample size diets prior to treatment were grain-free. That skews the results. As well, that treatment was not standardized. For instance, some dogs received furosemide (water pill), some dogs received ACE inhibitors, and some dogs received taurine. Honestly, the only standardization appeared to be switching dogs to grain-based diets. 

Additionally, we find it disturbing that the FDA went so far at one point to thank three researchers for their time and dedication. 

So, when we combine the healthy, but skewed sample size, the close working relationship of the FDA and three researchers, and the issues that come with open reporting, we are pretty sure that the information given to the agency only came from a few sources. 

As to the about-face, pure speculation might be that the FDA realized the error of its ways, but may not own up to it. 

The about-face also could have been from pressure applied by the pulse producer industry. According to excellent reporting by H.S., “In fact, the USA Dry Pea & Lentil Council’s 2019 annual report stated the organization ‘convinced the FDA to clarify their language about their concerns and minimize the damage to the industry.’” 

You may be thinking, “Of course! Industry pressure!” Industry pressure occurs on all sides. Many of the major pet food manufacturers that developed the standardized grain-inclusive formulations have influence with the FDA. 

We are all still confused, but go with what the FDA is saying now: While adverse event numbers can be a potential signal of an issue with an FDA regulated product, by themselves, they do not supply sufficient data to establish a causal relationship with reported product(s).

BSM Partners

BSM Partners work with Zignature, one of the 16 pet food brands implicated by the FDA. 

In so many words, BSM stated that the increase of DCM diagnoses in pure and mixed breeds did not correlate with grain-free food sales, which experienced exponential growth over a decade. 

Before you dismiss their findings as being influenced, they did their due diligence. 

They identified approximately 256 board-certified veterinary cardiologists in 2020 in the United States. After applying some parameters, they contacted 88 referral hospitals and veterinary schools. Only 14 out of the 88 participated and only three provided age and breed data. 

Those numbers may appear limiting, but actually they are not. BSM reviewed over 68,000 cardiology patient reports over 19 years. 

If we compare BSM and FDA findings, we believe BSM had better epidemiological results and more information from more sources.

Additionally

The Association for Pet Obesity Prevention generates an annual survey of pet owners and veterinarians. In 2017, 46% of dog owners believed that limited grain or grain-free diets were healthier for dogs, 12% did not, and 43% were unsure. At that time, only 21% of veterinarians thought it to be true, 63% did not, and 16% were unsure. 

The 2021 survey results shocked us. 27% of dog owners said yes, 38% said no, and 35% were unsure. On the veterinary side, only 7% said yes, 88% said no, and only 5% were unsure. 

The results from this question almost appear to be in direct contrast, “Have you changed dog food brands due to the ‘grain-free’/DCM (heart disease) controversy?” 79% from both camps said “No.”

Misperception Continues to Reign

When this controversy came to the forefront in 2018, Hemopet was circumspect because of the origin. It was simply conjecture at that point in time, not based on actual scientific evidence. Let’s focus on one of the three thanked by the FDA. 

As you may recall in mid-2018, Dr. L.F. – who is an animal nutrition researcher at Tufts University and has created diets for several large pet food manufacturing conglomerates – wrote a blog post and stated, “However, recently, some astute cardiologists noticed higher rates of DCM including Golden retrievers and in some atypical dog breeds. They also noticed that both the typical and atypical breeds were more likely to be eating boutique or grain-free diets, and diets with exotic ingredients – kangaroo, lentils, duck, pea, fava bean, buffalo, tapioca, salmon, lamb, barley, bison, venison, and chickpeas. Even some vegan diets have been associated. It has even been seen in dogs eating raw or home-prepared diets.” 

We are not saying this hypothesis is wrong. However, a very high threshold was set here, that included a long list of many types of foods. 

In our opinion, the media was used to bypass scientific research protocols about a very serious and grave illness, and what we believe became biased confirmatory research that continues to this day.

Another commentary addressed in the same blog post creates more concern: 

“Many pet owners have, unfortunately, also bought into the grain-free myth. The fact is that food allergies are very uncommon, so there’s no benefit of feeding pet foods containing exotic ingredients. And while grains have been accused on the internet of causing nearly every disease known to dogs, grains do not contribute to any health problems and are used in pet food as a nutritious source of protein, vitamins, and minerals.”

Two things. First, the protein qualities of grains and legumes (for that matter) do not compare directly to those in meat. 

Second, stomach issues and skin conditions were the top two claims according to the 2019 survey from Healthy Paws Pet Insurance. Many stomach and skin conditions have been linked to food sensitivities and intolerances. In retrospect, we are surprised that there was no outcry from veterinary dermatologists. 

H.S.’s article published in mid-2022 confirms that: 

“In a June 2018 email to [FDA veterinary officer J.J., L.F. attached a document showing that her center had instructed vets to report cases to the FDA, ‘If patient is eating any diet besides those made by well-known, reputable companies or if eating a boutique, exotic ingredient, or grain-free (BEG) diet’.” 

On a sidenote, there have been direct quotes in the media from L.F. 

Our point: without the proper research conducted prior to any media announcement, more harm than good could have been caused. We likely will never know the true impact.

Please keep these items in your mind for our upcoming discussions…

Some issues with foods and the dog body. 

#1. Breed

#2. Size

#3. Age

#4. Genetics

#5. How different types of food processing (kibble, canned, raw, dehydrated, home prepared) can impact the amount of amino acids present and bioavailable like methionine, cysteine, taurine and creatine whether or not they are essential or nonessential? The same issue can be applied to vitamins, minerals and other supplements. 

#6. How bioavailable and digestible is the processed food? 

#7. How the body processes food such as converting the essential amino acids into other amino acids? 

#8. Ingredients listed.

Misstep 2018 – 2022: Genetics

BSM Partners’ report from 2022 addresses an excellent point, “There was no significant correlation between grain-free pet food sales and Small Breed and Mixed Breed group. While this small cohort suggests an uptick, it is not correlated to grain-free pet food sales from 2011–2019. This may be a potential explanation for increasing diagnosis of DCM in this cohort. Moreover, these dogs were not genetically tested to rule out any potential inherited breeds or genetic mutations; nor was the diet history, medical care, concurrent illnesses, or possible predisposing medical conditions known about these dogs. Further studies should genetically test mixed breed and atypical dogs diagnosed with DCM to potentially rule out a genetic component as well as, larger studies performed to further investigate if DCM is increasing in mixed and small breed dogs nationwide or regionally. A slight decrease in DCM seen in inherited breeds in the data from the three hospitals that provided breed data may be due to improved breeding practices and deselection of breeding individual dogs with a history of DCM.”

Let’s remember, too, that the mixed breed category includes the oft referred to “hybrid” dogs that have gained popularity over the past two decades.  

Another Misstep 2018 – 2022: Taurine & Carnitine

Taurine is a nonessential amino acid for dogs. Dogs make it in their livers out of the essential amino acid, methionine, and another nonessential amino acid, cysteine.

Carnitine is another nonessential amino acid produced in the body from amino acids methionine and lysine. Compared to taurine, carnitine was put to the backburner. So, we will focus here on taurine as an example. 

Several researchers looking into DCM determined that whole blood and plasma taurine concentrations are not indicators of diet-associated DCM in breeds not known to have hereditary or taurine deficient DCM. Of course, the caveat that more research needs to be done is always stated. Even though, everyone likely has already picked up this point as truth.

But, maybe the current reference ranges are incorrect or incomplete and dogs may need more taurine or one of its precursors, or more or less of another amino acid? We just don’t know. We do know, in fact, that Golden Retrievers may need more taurine in their diets than other breeds. 

Prior to any treatment for DCM, veterinarians and veterinary cardiologists preferably should follow the same standard protocol of confirming diagnosis with echocardiograms and taking a blood sample to send to a reference laboratory for a complete amino acid profile. A database with a more complete picture is needed which we can retrospectively analyze to guide future research, to determine if circulating whole blood or plasma taurine or its precursors are indicators of DCM or another disease, to supplement or decrease a particular amino acid instead, and to determine reference ranges based on breed, age or size. 

Here is a good example. Greyhounds have a higher reference range of acceptable circulating creatinine in the blood compared to healthy mixed breed dogs. Creatinine is the byproduct of nonessential amino acid, creatine, and is used as an indicator for kidney disease.

Regardless, pet food manufacturers started adding taurine to their formulations. So was the dog diagnosed with DCM prior to or after the additional taurine? How far had the disease progressed by the time of diagnosis? The variables here seem endless. 

Two Tracks of Research

We’ve noticed two tracks of research developing over the past few years: deliberate, considerate, meaningful, and complex versus trying to prove a point (confirmation bias). 

We compared two studies that were published four months apart. Note that there are many relevant research studies here. 

D.A., L.F. and colleagues evaluated four client-owned breeds: Doberman Pinschers, Golden Retrievers, Miniature Schnauzers and Whippets. Dobermans have a predisposition for hereditary DCM. Golden Retrievers have been stated to have a higher prevalence of taurine deficiency that may or may not be linked to genetics. Miniature Schnauzers and Whippets are not known to have a genetic predisposition to DCM or taurine deficiency.

23 out of the 37 Doberman Pinschers had a DCM 1 or DCM 2 mutation based on genetic testing.

They divided the breeds into two groups: grain-free and grain-inclusive. As well, they had two more groups. “FDA-PLP” for FDA listed ingredients of concern (peas, lentils, or potatoes) in the top 10 listed ingredients in the food, and “NoFDA‐PLP” for those foods that did not list any of those ingredients as one of the top 10 listed on the bag. 

The best way to explain grain-inclusive FDA-PLP is to imagine if the third ingredient listed was wheat, but the fourth was peas. So, it is grain-inclusive, but contains an ingredient considered “concerning”. 

(By the way, we checked the FDA DCM webpages for the use of the word “concern”. As far as we could find, the agency uses it once, but not in the same context, “We understand the concern that pet owners have about these reports…”.) 

We agree with the inclusions and exclusions. Dogs had to be considered healthy, and be eating a commercial dog food for at least six months. Dogs excluded were receiving taurine supplementation or cardiac medications, pregnant, lactating, in heat, or had known cardiac disease.

The good news is that there were no differences in echocardiographic variables or whole blood taurine noted between the dogs eating different diet types. Dogs eating grain-free or the FDA-PLP had higher cardiac troponin levels. That’s concerning as it is a blood indicator for heart attack risk or heart injury. Additionally, dogs eating FDA-PLP had significantly more ventricular premature complexes (skipped beats, flutters, etc.) compared to dogs eating NoFDA-PLP. 

But, this is where they lost us: “The study was not designed to evaluate each breed individually”.

Really? Have we not learned anything? Yes; Doberman Pinschers and Miniature Schnauzers are both German breeds…but we are at a loss from there as to why they would purposely choose these breeds, pool them, but disregard them as individual breeds. Why? 

That type of research continues today: comparing dogs on “nontraditional diets” versus dogs on “traditional diets.” It is just simple research applied to a complex condition. 

In our comparison study, we are looking at W.M., J.T. and colleagues who researched minimum dietary methionine requirements in adult Miniature Dachshunds, Beagles, and Labrador Retrievers using the indicator amino acid oxidation (IAAO) technique when cysteine is provided in excess. 

Their premise is that the National Research Council’s (NRC) current recommendations are miscalculated because those are based on fairly old studies completed with puppies or other studies where dogs displayed no clinical signs of deficiency. 

They also surveyed the entire pet food situation, having previously estimated other amino acids using IAAO. Their research revealed that phenylalanine requirements might be lower than the current NRC recommendations, but that tryptophan, lysine and threonine are higher. Additionally, they carefully discussed some of the ingredients in the basal diet and how those could impact amino acids and overall digestibility. 

This particular study determined that the current NRC recommendations for methionine are adequate for Miniature Dachshunds, but that Beagles and Labrador Retrievers need more methionine. For anyone thinking they cannot even cook for themselves, this team sought an “all breed” pooled recommendation.

More studies definitely need to be completed that look at different types of diet formulations, how the food is processed, and its digestibility. 

Conclusion

Even though the FDA has put DCM in companion dogs aside for the present, we do not foresee the topic being resolved or its ‘hot button’ nature going away. Remember that the FDA said it is waiting for meaningful research, which will take time. 

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