Written by: Danielle Conway DVM, CCRP, CVA, VSMT, Nutrition Residency Trained
Ivan Sosa Samper DVM, DACVIM (Cardiology)
Kelly Wessberg, DVM, DACVIM (Cardiology)
What Is Dilated Cardiomyopathy?
Dilated cardiomyopathy (DCM) is a genetic disease of the heart muscle. In addition to a genetic predisposition in certain dog breeds, there are other conditions that can show similar lesions as seen with DCM. These include a nutritional deficiency, certain drugs, or even infectious or inflammatory diseases that are severe enough to damage the heart.
As DCM progresses, it causes the muscle to be less efficient at pumping. This results in dilated heart chambers that cannot move blood, and ultimately leads to the development of congestive heart failure.
There are certain breeds that are genetically predisposed to DCM. These breeds are often screened for the disease with an echocardiogram (heart ultrasound) and a Holter monitor, as there is an ‘occult’ stage where dogs don’t show clinical signs, and diagnosing and treating the disease early can improve the outcome.
What Are the Signs of DCM?
Unfortunately, in the early (occult) stages of DCM there are no clinical signs.
In the advanced stages of disease: shortness of breath, coughing, decreased energy, collapse, arrythmias, exercise intolerance and death. By the time clinical signs are present, the disease is advanced, and the prognosis is poor.
Why Is There an FDA Investigation?
Most cases of genetic DCM are seen in breeds predisposed to the disease. Starting in 2013, cardiologists noticed a rise in the incidence of this condition in breeds not usually genetically predisposed. The commonality amongst these cases was the consumption of a grain free diet, and the improvement of cardiac function after changing the diets, which is not something that happens in dogs with genetic DCM. This was also a time where grain free diets were reaching heightened popularity.
The FDA officially launched its investigation on January 1, 2014.
What Do We Know So Far and How Did We Get Here?
The Quick Notes:
- There are 574 cases and counting of DCM that are thought to be diet related. In these cases:
- More than 90% of the diets were grain free.
- 93% contained peas or lentils as a main ingredient.
- 42% contained potato as a main ingredient.
- 88% were dry foods.
- Top reported breeds include:
- Golden Retrievers, Mixed Breed dogs, Labrador Retrievers, Great Danes, Pit bulls, German Shepherds, and Doberman Pinschers
Bear in Mind:
- Correlation does not always mean causation.
- This is not a simple issue, and there is a lot we do not yet know.
- It’s not all grain free diets.
- Not every dog eating a grain free diet will develop DCM.
- It remains uncertain exactly why these diets are causing a problem.
- The vast majority of dogs eating the food listed have not developed DCM.
- It’s not just dogs – a few cats have also been reported.
- The best screening tool is an echocardiogram.
- Not all dogs affected have low taurine levels – there seem to be other nutrients at play.
- It takes 6+ months for the changes to develop (so if a dog was on a grain free diet for one month, we wouldn’t see the changes yet).
- If it is nutrition-responsive DCM, it is reversible if caught in time, but it takes 6-12 months for affected dogs to fully recover.
- Not all grain free diets are associated with this issue. If you are concerned, an echocardiogram is the best way to determine whether there is a problem.
Correlation vs. Causation
Before we go any further, we want to explain a very complex scientific concept in simple terms: correlation vs. causation.
Causation is “cause” and “effect,” meaning that the outcome you are experiencing is directly the result of a specific cause. e.g. smoking causes lung cancer.
Correlation is a mutual relationship, or link, between two variables, but one does not cause the occurrence of the other. e.g. both smoking and alcohol consumption are linked to lung cancer, but only smoking (not alcohol consumption) causes lung cancer.
Nutrients vs. Ingredients
I also want to differentiate between nutrients and ingredients. All living beings have nutrient requirements, not ingredient requirements. Due to the successful marketing of certain pet food companies, pet owners are becoming more concerned about feeding their furry companions a diet with ingredients that they find acceptable, rather than making sure a diet contains the appropriate nutrients and calories for their companion’s age and lifestyle. Ingredients can and should provide nutrients, but ingredients are not the only important aspect of a diet.
Correlation and Causation with DCM and Grain Free Diets
With regard to nutritional DCM and the grain free diet issue, there is a combination of correlation and likely causation occurring. Which is why it is so confusing.
It is not accurate to claim that all grain free diets are bad and cause heart disease. However, it is appropriate to say that grain free diets containing exotic proteins, large quantities of pea, chick pea, or potato, and are formulated by companies in response to a perceived desire in the market.
Nutritionists have been advising clients away from exotic ingredient boutique companies who do not consult with veterinary nutritionists. The reason we have been cautioning clients away from these diets is because we know from experience that balancing these exotic ingredients is challenging. Our 7+ years of veterinary schooling supports our knowledge of the diseases that may occur as a result of nutritional deficiencies.
For example, we know that kangaroo and lamb have odd amino acid profiles and often requires supplementation and careful attention to cysteine and methionine. We know that high total dietary fiber levels can bind up certain nutrients, and diets using ingredients high in fiber may require additional supplementation of key nutrients. We know that B vitamins and antioxidants should be plentiful within a diet and should be within safe levels.
Why are Grain Free Diets Only Affecting a Small Percentage of Dogs?
Another question we have not addressed yet is that grain free diets have been around for a long time, and there are millions of animals on grain free diets, so why is diet-associated DCM only affecting a relatively small percentage of that population?
We do not have the answer to that question yet.
Your best long-term defense is regular wellness exams with your primary care veterinarian and a consultation with a veterinary nutritionist if you have concerns.
What Is the FDA Doing About It?
From the most recent FDA update June 27 2019:
“Veterinarians, animal nutritionists, epidemiologists and pathologists are working with board certified veterinary cardiologists and veterinary nutritionists to better understand the clinical presentation of the cases and potential ties to diet. The agency has also been in contact with pet food manufacturers to learn more about product formulation and concentration of certain ingredients in order to help further the investigation. In addition, we are analyzing information from case reports submitted by pet owners and veterinarians. We will continue to work with all of these stakeholders to help advance our ongoing investigation.”
This situation is very reminiscent of the pet food Melamine recall of 2007. We have learned a lot since then, and hopefully the FDA’s quick response and release of the correlated food list will help us find the answers faster than withholding the information until the exact cause is confirmed. Now we can all work together: pet owners, veterinary medical professionals, pet food companies and the FDA.
What Should I Do If I Am Feeding a Grain Free Diet or If I Am Feeding a Diet That Is On the FDA Report?
If your dog has been on a grain free diet that has been listed on the FDA list, start by contacting your veterinarian.
We also recommend a consultation with a veterinary cardiologist and ideally a veterinary nutritionist. This may seem extreme if your dog is not experiencing any clinical signs, but DCM often exists before heart failure sets in and DCM often is not associated with a heart murmur.
Simply stated, you need to look inside the heart and assess its function. The only way to do that is with an echocardiogram (heart ultrasound). Like other diseases, it is best to catch it and intervene early.
If your pet is coughing or experiences exercise intolerance, you should make an appointment with your vet ASAP. If your pet collapses, or faints, or experiences shortness of breath you should bring your pet to the closest veterinary emergency room.
This is Serious
Please keep in mind that is very complex and the FDA and veterinary community are just starting to investigate this issue. All dogs on the FDA list may not have diet related DCM; in some, the case could be genetic.
Also something to keep in mind is that this is a newer problem, so while we should not panic, we should still take the issue seriously.
Pet Food Companies on the List
Most of the major pet food companies are listed on the FDA diet list. It is not concerning to us if a diet shows up once or twice (remember correlation vs causation?) However, the companies that continue to show up repeatedly are the ones the veterinary community is worried about with good reason. It is our hope that those companies showing up repeatedly are being proactive and addressing the issues where they can.
What Do We Expect of the Companies Listed on the FDA List?
Work with the FDA to provide them any information they need so we can help to identify the cause.
Simply stated, this is not a conspiracy. It is a real problem. One that we need more information on, but one we all should be taking seriously and should all be doing everything we can to help.
There are wonderful companies out there who make grain free diets who have responded responsibly to the FDA list and investigation and as a result, Dr. Conway is comfortable continuing to recommend their products.
The grain free diet trend overall has been over marketed, and not all dogs should avoid grains; however, some individuals do have a sensitivity and do better without gluten in their diets.
How Do I Choose a Pet Food Company I Can Trust?
At minimum, the company should have good manufacturing processes in place that include testing and holding all ingredients coming into the plant and all products going out of the plant. The diets should be free of contaminants and bacteria, and meet an AAFCO (American Association of Feed Control Officials) claim. A diet should be at least AAFCO formulated and better yet AAFCO tested. AAFCO is not perfect but it is a starting point.
If the company uses a co-packer to pack and distribute their diet, they should be able to tell you who their co-packer is.
The diets should be formulated by someone with advanced education and training in the formulation of dog and cat diets. Ideally these recipes would be evaluated by a board-certified veterinary nutritionist.
The diets should regularly be sent out for analysis to ensure that what is in the bag matches the computer formulation. Companies get a gold star if digestibility testing is performed, have a commitment to environmental sustainability, support the veterinary community, and perform or support funding for veterinary nutrition research and the advancement of veterinary nutrition.
How do you know if your pet food is following these recommendations? Call and ask! Please visit this site for a resource with a list of questions for pet food companies: https://www.wsava.org/wsava/media/arpita-and-emma-editorial/selecting-the-best-food-for-your-pet.pdf
Still Confused on What to Feed Your Pet?
Discuss your pet’s diet with your veterinarian and if you still have questions or would like additional guidance, please find a veterinary nutritionist near you.
References for Further Knowledge
Dilated Cardiomyopathy and Grain-Free Diets: Thoughts on the FDA Update by Dr. Justin Shmalberg
FDA Provides Third Status Report on Investigation into Potential Connection Between Certain Diets and Cases of Canine Heart Disease
Questions & Answers: FDA Center for Veterinary Medicine’s Investigation into a Possible Connection Between Diet and Canine Heart Disease
Diet-Associated Dilated Cardiomyopathy (DCM): Update, July 2019 by Lisa M. Freeman, DVM, PhD, DACVN