Dilated Cardiomyopathy (heart disease) in Dogs and Why Some Dogs Eat “Exotic” Ingredients

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In July 2018, the United States Food and Drug Administration (FDA) issued a public notification about an uptick of reports of canine dilated cardiomyopathy (DCM) – a type of heart disease that can lead to congestive heart failure – in dogs eating certain pet foods containing peas, lentils, legume seeds or potatoes.

In case you are unfamiliar with DCM, the condition can be hereditary and/or dietary, and also can be idiopathic (cause unknown). In general, DCM occurs when an insufficient amount of the amino acids cysteine and methionine are ingested, which dogs use to synthesize taurine in the liver. Taurine is important as it prevents or slows the progression of DCM. 

Due to the FDA’s announcement, some researchers quickly pointed to grain-free formulations as the culprit.

Dr. Dodds and Hemopet have urged caution about jumping to any conclusions in earlier postings. We referenced previous studies that demonstrated lower taurine concentrations in the blood from dogs eating formulations that contained combinations of grains and proteins such as barley and turkey or lamb and rice, and one that showed beet pulp as possibly instigating lower taurine concentrations.  

Since July, two notable studies have been published.

Adin et al., “Echocardiographic phenotype of canine dilated cardiomyopathy differs based on diet type”

  • Retrospective analysis of 48 dogs diagnosed with DCM and known diet history.
  • Compared dogs eating grain-free diets to dogs eating grain-based diets.
  • Taurine deficiency was not identified in the grain-free fed dogs, and presence of congestive heart failure was not different between groups.
  • Dogs eating grain-free diets had more advanced cardiomyopathic changes than did dogs eating grain-based diets.
  • Some dogs improved from switching from one grain-free diet to another. This suggests that DCM was not particularly linked to grain-free diets. 

Kaplan, Stern et al., “Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets”

  • 24 golden retrievers with documented taurine deficiency and DCM.
  • 23 of the dogs were originally fed kibble diets that were either grain-free, legume-rich, or a combination.
  • All original diets included a complete and balanced claim to meet Association of American Feed Control Officials (AAFCO) dog food nutrient standards, yet none of them had been subjected to feeding trials. Additionally, none of the diets met the World Small Animal Veterinary Association (WSAVA) standards. The researchers considered the diets to be non-traditional even though two dogs ate chicken.
  • Many dogs in the study were consuming less than their predicted needs based on their maintenance energy requirement (MER) and also less than the manufacturer’s recommendations. Thus, the dogs were not getting enough amino acids for proper taurine synthesis.  
  • At least 21 dogs had a change in diet and received taurine supplementation for the study. For 3 dogs, follow-up data did not include diet information. 17 switched to a grain-inclusive diet. 4 were switched to another grain-free diet. 13 of the dogs were additionally prescribed L-carnitine, another amino acid. 11 dogs were diagnosed with congestive heart failure and prescribed diuretic therapy (furosemide).
  • Limitations to the study include a lack of standardization across all cases, so researchers could not clearly identify any treatment-specific differences from their results.
  • According to the researchers, 23 out of the 24 dogs had improvement of echocardiographic parameters and normalization of taurine concentrations following diet change and taurine supplementation.

We have some reservations with the Kaplan, Stern et al. study. First, two variables – taurine supplementation and diet change – were introduced in at least 21 dogs. In 13 possible cases, the researchers introduced three variables: taurine supplementation, L-carnitine supplementation and diet change. 11 dogs had possibly taurine supplementation, diuretic therapy, diet change, and/or L-carnitine supplementation. Therefore, it is impossible to identify the driving factor in the improvement of the dogs’ conditions.

Secondly, a uniform diet change was not directed or applied by the researchers.

Finally, they admit that many dogs initially were not fed enough of their original diets to meet MER or even the minimum recommendations by the manufacturer.

Freeman, Stern, Fries, Adin and Rush, “Commentary: Diet-associated dilated cardiomyopathy in dogs: what do we know?”

Drs. Adin and Stern – two of the primary researchers who conducted the studies above – teamed up with Drs. Freeman, Fries and Rush for this article published in the Journal of American Veterinary Medical Association.

In this article, the authors veer away from the grain-free theory as the main reason, and towards a diet that Dr. Freeman and group have coined,“BEG”, an acronym for “boutique, exotic and grain-free”. This acronym may be viewed as inflammatory rhetoric. The authors include kangaroo, duck, buffalo, salmon, rabbit, venison, lamb, bison, fava beans, peas, tapioca, barley and chickpeas as example ingredients. This is a rather long list of ingredients.

Further along in the article the authors explain, “Exotic ingredients have different nutritional profiles and different digestibility than typical ingredients and have the potential to affect the metabolism of other nutrients. For example, the bioavailability of taurine is different when included in a lamb-based diet compared with a chicken-based diet, and can be affected by the amount and types of fiber in the diet.”

We completely agree with them on that point. It is an area of research that needs further investigation.

However, when going over the Kaplan/Stern et al. report, they stated the following, “The increased use of previously uncommon animal protein sources such as rabbit, venison, bison, lamb, and wild boar, especially in the category of diets marketed as grain-free, warrants characterization of their typical amino acid profiles including the degree and nature of any variability. In fact, certain meats are unexpectedly low in taurine (such as rabbit) or low in sulfur amino acid precursors (such as lamb meal). In addition, the bioavailability of taurine and its precursors in many animal protein sources is not known. Many of the baseline diets in this study contained animal protein sources that until recently were not commonly found in canine diets.”

We decided to review the animal protein sources available in Table 2: 10 dogs ate pork, 8 dogs ate lamb, 1 dog ate beef, 1 dog’s protein was unknown, 1 dog ate venison, 1 ate turkey, 1 ate salmon, 1 dog had a regional red variety, and 2 ate chicken. 2 of the dogs were on rotated diets, which explains why the total is 26 instead of 24.

We agree that pork, venison and salmon are relatively new proteins introduced to commercial canine diets. However, we do not consider them to be “exotic”. Furthermore, all 24 dogs were diagnosed with DCM, including those eating chicken and beef. None of the dogs were eating rabbit. The connection between lamb and lower taurine concentrations in the blood of certain breeds like golden retrievers was established over a decade ago.

Even though this group of researchers acknowledges prior research, lack of knowledge, the complexity of food interaction, that processing and heat can affect amino acids, that bioavailability varies between animal muscle proteins, that taurine deficiency may be related to cardiotoxic ingredients in the diet, and a host of other potential causes, they remain sharply focused on what they have coined as“BEG” diets.

Again, there is too much narrowcasting. We need to broaden our view and think about DCM and nutrition more holistically.

Why Companion Pet Parents Feed “Exotic” Ingredients

Now that we have discussed this speculation without firm conclusions,we have to remind ourselves why pet companion caregivers feed venison, pork, lamb, buffalo, rabbit and other so-called exotic ingredients. They are not doing it casually. Indeed, the prices for these proteins and plant-based ingredients can be relatively more expensive.

Pet companion caregivers are doing it because they notice that their dogs derive a variety of health benefits. For instance, it could be to prevent leaky gut syndrome, to help curb food sensitivities or intolerances to a particular grain or protein, or to maintain optimal weight and energy.

In fact, we pulled the NutriScan Food Sensitivity and Intolerance Test data for golden retrievers from January 2016 through December 2018. NutriScan tests a dog’s food sensitivity level to 24 of the most commonly ingested foods including beef (includes buffalo and bison), chicken eggs, corn, barley, wheat, millet, soy, oat/oatmeal, cow’s milk, salmon, lamb (includes goat), rabbit, venison, rice, chicken, quinoa, turkey, potato, sweet potato, peanut/peanut butter, pork, white-colored fish, duck and lentils (includes peas).

As you can see from the results, turkey and white-colored fish had the highest reactions. We assume that turkey and white-colored fish would be considered a non-exotic animal protein by the cardiology and nutrition researchers above, but they could possibly consider other fish an exotic ingredient.

It should be noted that there was no difference among the percentage of reactive foods between the golden retrievers eating commercial foods and those eating the raw, grain-free or home-prepared foods. In other words, food reactivities are based upon the individual dog’s sensitivities and not on the diet composition itself.

Additionally, 26 dogs were tested for whole blood taurine levels upon client request, as noted by the asterisks. All were mid-normal, except that three were slightly elevated (not supplemented with taurine beyond their diet level).

Parameter (1/2016-12/2018) Number of Golden Retrievers Comments
Total Number with NutriScan Testing 523 None had known cardiac disease or dysfunction; all healthy or had itching and/or bowel issues*

Commercial Cereal-Based (Kibble) Diet

273 (52%)

Variety of kibbles with and without canned foods

Raw Diet

133 (25%)

Variety of meats, fowl and fish plus some carbohydrates and vegetables

Grain-Free Diet

79 (15%)

Same as Raw Group

Home-Prepared Diet

38 (7%)

Same as Raw Group

Reactive Foods on Nutriscan Testing (24 key foods)

523 (total results) and the combination of Raw, Grain-Free and Home-Prepared diet groups (250) yielded the same breakdown of reactive foods

Highest (54-60%) = Turkey and White-Colored Fish. Medium = (44-48%) = Venison and Corn.
Lowest (11%) = Lamb and No food reactions

Total Number in Database (all Hemolife Diagnostics)

22,192

Includes any type of diagnostic test run at Hemopet/Hemolife during the 2-year period

If you are concerned, have your veterinarian take a blood sample to measure the taurine levels in whole blood and send it to a diagnostic laboratory experienced with the appropriate reference ranges for circulating taurine. If the levels are lower than normal for dogs, please discuss the appropriate next steps with your veterinarian. As well, please send the information on your dog, including the food you are feeding, breed, health regarding canine heart disease and retinal degradation, age and weight to the FDA – no matter what the results are. You and your dog would potentially be helping millions of other dogs.

References

Adin, Darcy, et al. “Echocardiographic Phenotype of Canine Dilated Cardiomyopathy Differs Based on Diet Type.” Journal of Veterinary Cardiology, vol. 21, Feb. 2019, pp. 1–9., doi:10.1016/j.jvc.2018.11.002. https://www.sciencedirect.com/science/article/pii/S1760273418300882

Backus, R.C., et al. “Low Plasma Taurine Concentration in Newfoundland Dogs Is Associated with Low Plasma Methionine and Cyst(e)Ine Concentrations and Low Taurine Synthesis.” The Journal of Nutrition, vol. 136, no. 10, 1 Oct. 2006, pp. 2525–2533., http://academic.oup.com/jn/article/136/10/2525/4746691.

Delaney, S.J., et al. “Plasma and Whole Blood Taurine in Normal Dogs of Varying Size Fed Commercially Prepared Food.” Journal of Animal Physiology and Animal Nutrition, vol. 87, no. 5-6, June 2003, pp. 236–244.,http://www.ncbi.nlm.nih.gov/pubmed/12752830.

“FDA Investigating Potential Connection Between Diet and Cases of Canine Heart Disease.” U.S. Food and Drug Administration, Center for Biologics Evaluation and Research, 12 July 2018, http://www.fda.gov/AnimalVeterinary/NewsEvents/CVMUpdates/ucm613305.htm.

Freeman, Lisa M., et al. “Diet-Associated Dilated Cardiomyopathy in Dogs: What Do We Know?” Journal of the American Veterinary Medical Association, vol. 253, no. 11, 1 Dec. 2018, pp.1390–1394., doi:10.2460/javma.253.11.1390. https://avmajournals.avma.org/doi/abs/10.2460/javma.253.11.1390.

Kaplan, Joanna, et al. “Taurine Deficiency and Dilated Cardiomyopathy in Golden Retrievers Fed Commercial Diets.” PLOS One, vol. 13, ser. 12, 13 Dec. 2018. doi:10.1371/journal.pone.0209112. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0209112.

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