Excerpted from “A broken heart: Risk of heart disease in boutique or grain-free diets and exotic ingredients” by Lisa Freeman, DVM, PhD, ACVN, head of the Nutrition Department at Tufts Cummings School of Veterinary Medicine (6/4/2018):
Heart disease is common in our companion animals, affecting 10-15% of all dogs and cats, with even higher rates in Cavalier King Charles Spaniels, Doberman Pinschers, and Boxer dogs. Most nutritional recommendations focus on treating dogs and cats with heart disease and there is much less information on the role of diet in causing heart disease. However, a recent increase in heart disease in dogs eating certain types of diets may shed light on the role of diet in causing heart disease. It appears that diet may be increasing dogs’ risk for heart disease because owners have fallen victim to the many myths and misperceptions about pet food. If diet proves to be the cause, this truly is heart-breaking to me.
In my 20 years as a veterinary nutritionist, I’ve seen vast improvements in our knowledge about pet nutrition, in the quality of commercial pet foods, and in our pets’ nutritional health (other than the unfortunate rise in obesity). However, in the last few years I’ve seen more cases of nutritional deficiencies due to people feeding unconventional diets, such as unbalanced home-prepared diets, raw diets, vegetarian diets, and boutique commercial pet foods. The pet food industry is a competitive one, with more and more companies joining the market every year. Marketing is a powerful tool for selling pet foods and has initiated and expanded fads, that are unsupported by nutritional science, including grain-free and exotic ingredient diets. All this makes it difficult for pet owners to know what is truly the best food for their pet (as opposed to the one with the loudest or most attractive marketing). Because of the thousands of diet choices, the creative and persuasive advertising, and the vocal opinions on the internet, pet owners aren’t able to know if the diets they’re feeding have nutritional deficiencies or toxicities – or could potentially even cause heart disease.
Dilated cardiomyopathy or DCM occurs in cats where it is associated with a nutritional deficiency (see below). DCM is a serious disease of the heart muscle which causes the heart to beat more weakly and to enlarge. DCM can result in abnormal heart rhythms, congestive heart failure (a build-up of fluid in the lungs or abdomen), or sudden death. In dogs, it typically occurs in large- and giant-breeds, such as Doberman pinschers, Boxers, Irish Wolfhounds, and Great Danes, where it is thought to have a genetic component. Recently, some veterinary cardiologists have been reporting increased rates of DCM in dogs – in both the typical breeds and in breeds not usually associated with DCM, such as Miniature Schnauzers or French Bulldogs. There is suspicion that the disease is associated with eating boutique or grain-free diets, with some of the dogs improving when their diets are changed. The US Food and Drug Administration (FDA) Center for Veterinary Medicine and veterinary cardiologists are currently investigating this issue.
Is diet the cause?
It’s not yet clear if diet is causing this issue. The first thought was a deficiency of an amino acid called taurine. DCM used to be one of the most common heart diseases in cats but in 1987, it was discovered that feline DCM was caused by insufficient taurine in the diet. It was shown that DCM in cats could be reversed with taurine supplementation, and now all reputable commercial cat foods contain enough taurine to prevent the development of this lethal disease. We still occasionally see taurine deficiency-induced DCM in cats but it is usually when owners are feeding a vegetarian or home-prepared diet, supplemental diets, or a diet made by a manufacturer with inadequate nutritional expertise or quality control.
In dogs, Golden Retrievers and Cocker Spaniels were found to be at risk for DCM caused by taurine deficiency, and one study showed that Cocker Spaniels with DCM improved when given taurine supplementation. Since then, additional studies have shown associations between dietary factors and taurine deficiency in dogs, such as lamb, rice bran, high fiber diets, and very low protein diets. And certain other breeds were found to be at increased risk for taurine deficiency and DCM, including Newfoundlands, St. Bernards, English Setters, Irish Wolfhounds, and Portuguese Water Dogs. The reasons for taurine deficiency in dogs are not completely understood but could be reduced production of taurine due to dietary deficiency or reduced bioavailability of taurine or its building blocks, increased losses of taurine in the feces, or altered metabolism of taurine in the body.
No matter what the reason, the number of dogs with taurine deficiency and DCM subjectively appeared to decrease since the early 2000’s. 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.
So, is this latest rash of DCM caused by taurine deficiency? Most of these affected dogs were eating boutique, grain-free, or exotic ingredient diets. Some of the dogs had low taurine levels and improved with taurine supplementation. But even some of those dogs that were not taurine deficient improved with taurine supplementation and diet change. Fortunately, cardiologists reported the issue to the FDA which is currently investigating this issue. [Note: Dr. Joshua Stern from the University of California Davis is conducting research on taurine deficiency and DCM in Golden Retrievers.
It’s not so simple
Currently, it seems that there may be two separate problems occurring – one related to taurine deficiency and a separate and yet unknown problem (with a third group of dogs likely having DCM completely unrelated to diet). Identifying the potential dietary factors contributing to DCM in the non-taurine deficient dogs is more difficult, but the FDA and cardiologists are hard at work trying to solve it. What seems to be consistent is that it does appear to be more likely to occur in dogs eating boutique, grain-free, or exotic ingredient diets.
Exotic ingredients are on the rise
Why are pet owners feeding these exotic ingredients? I think is it primarily because pet owners are falling victim to marketing which portrays exotic ingredients as more natural or healthier than typical ingredients. There is no truth to this marketing – and there is no evidence that these ingredients are any more natural or healthier than more typical ingredients. This is just good marketing that preys on our desire to do the best for our pets.
There is no proof that grain-free is better!
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.
Exotic ingredients are more difficult to use
Not only are the more exotic ingredients unnecessary, they also require the manufacturer to have much more nutritional expertise to be nutritious and healthy. Exotic ingredients have different nutritional profiles and different digestibility than typical ingredients, and also have the potential to affect the metabolism of other nutrients. For example, the bioavailability and metabolism of taurine is different in a lamb-based diet compared to a chicken-based diet or can be affected by the amount and types of fiber in the diet.
Small pet food manufacturers might be better at marketing than at nutrition and quality control
Making high quality, nutritious pet food is not easy! It’s more than using a bunch of tasty-sounding ingredients. The right nutrients in the right proportions have to be in the diet, the effects of processing (or not processing) the food need to be considered, and the effects of all the other ingredients in the food need to be addressed, in addition to ensuring rigorous quality control and extensive testing. Not every manufacturer can do this.
How could diet be increasing the risk for DCM?
What is the consistent factor between the diets being implicated in diet-related DCM? It may be related to companies’ inadequate nutritional expertise or rigorous quality control. We published a study several years ago in which we measured a single nutrient in 90 canned cat foods that all claimed to be nutritionally complete and balanced. We found that 15% of the diets were deficient in that nutrient (all of those diets were made by small companies). If companies don’t have the quality control to ensure all nutrients are at the minimum levels, deficiencies could occur and could contribute to DCM. However, these problems could also be related to problems with bioavailability or interaction with other ingredients in the diet (especially the more exotic ingredients, which are not as well studied or understood). And DCM could even be the result of an ingredient in the diet that is toxic to the heart. The FDA is investigating this potential association between diet and DCM…
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Excerpted from “It’s Not Just Grain-Free: An Update on Diet-Associated Dilated Cardiomyopathy” by Lisa Freeman, DVM, PhD, ACVN, head of the Nutrition Department at Tufts Cummings School of Veterinary Medicine (11/29/2018):
- It’s not just grain-free. This does not appear to be just an issue with grain-free diets. I am calling the suspected diets, “BEG” diets – boutique companies, exotic ingredients, or grain-free diets. The apparent link between BEG diets and DCM may be due to ingredients used to replace grains in grain-free diets, such as lentils or chickpeas, but also may be due to other common ingredients commonly found in BEG diets, such as exotic meats, vegetables, and fruits. In addition, not all pet food manufacturers have the same level of nutritional expertise and quality control, and this variability could introduce potential issues with some products.
- Most dogs being diagnosed with DCM do not have low taurine levels. Some owners continue to feed a BEG diet but supplement taurine thinking that this will reduce their risk for heart disease. In our hospital, we currently measure taurine in all dogs with DCM, but more than 90% of our patients with DCM in which taurine has been measured have normal levels (and the majority are eating BEG diets). Yet some of these dogs with DCM and normal taurine levels improve when their diets are changed. This suggests that there’s something else playing a role in most cases – either a deficiency of a different nutrient or even a toxicity that may be associated with BEG diets. Giving taurine is unlikely to prevent DCM unless your dog has taurine deficiency. And given the lack of quality control for dietary supplements, you can introduce new risks to your dog if you give a supplement without evidence that she needs it.
- Raw diets and homemade diets are not safe alternatives. Out of concern, some owners are switching from BEG diets to a raw or home-cooked diet. However, we have diagnosed DCM in dogs eating these diets too. And raw and home-cooked diets increase your dog’s risk for many other health problems. So, forego the raw or home-cooked diets and stick with a commercial pet food made by a well-established manufacturer that contains common ingredients, including grains. If your dog requires a home-prepared diet for a medical condition or you feel strongly about feeding one, I strongly recommend you consult with a Board-Certified Veterinary NutritionistTM (acvn.org). However, because home-cooked diets are not tested for safety and nutritional adequacy like good quality commercial diets, deficiencies could still develop.
Current thoughts on DCM
Currently, it appears that there may be three separate groups of dogs with DCM (although this may change as we learn more). I am listing them in the approximate frequency that we are currently seeing them in our hospital:
- Diet-associated DCM with normal taurine levels. While this form of the disease was first identified in dogs of breeds not predisposed to DCM that are eating BEG diets, it appears to also occur in dogs of typical DCM breeds that are eating a BEG diet.
- Primary DCM in predisposed breeds that is unrelated to diet. This is the traditional, genetically-related DCM in typical breeds, such as the Doberman Pinscher, Boxer, Irish Wolfhound, and Great Dane.
- Diet-associated DCM with taurine deficiency: This is the least common form we are seeing in our hospital. This appears to happen both in breeds predisposed to DCM and breeds that are not predisposed to DCM.
We still have a great deal to learn about diet-associated DCM. However, I’m providing answers to some common questions I’ve been getting based on what is currently known:
- What’s causing diet-associated DCM in dogs? For the vast majority of dogs, we do not yet know what is causing this disease. There are definitely some dogs with DCM that have low taurine levels, many of which will improve with taurine supplementation and change of diet. For dogs that have normal taurine levels, however, other nutritional deficiencies may be present. Some nutritional deficiencies can affect the heart’s normal function, so an insufficient amount of these nutrients (or reduced bioavailability) in the diet could cause heart disease. Diet-associated DCM could also be due to an ingredient in the food that is toxic to the heart. The FDAand many researchers are actively studying this issue so that it can be solved as quickly as possible.
- My dog was diagnosed with DCM. What should I do? Ask your veterinarian to measure taurine levels and give heart medications as directed by your veterinarian. If your dog is eating a BEG diet or other unconventional diet (including vegetarian, vegan, or home-prepared diets), I recommend following the steps outlined in my previous post, including switching to a non-BEG diet. Three updates to my previous post are:
- Taurine supplements: Consumer Lab is expected to release a report on independent quality control testing of taurine supplements in late 2018. Given the lack of quality control for dietary supplements (human and pet), having these results will be very useful to find good quality products for dogs that require taurine supplementation. Your veterinarian or veterinary cardiologist can help you determine an optimal dose for your dog.
- Other dogs in the household: We are now recommending that other dogs in the household of dogs with DCM that are eating the same BEG diet be screened by their veterinarian since their hearts could also be affected (even if they are showing no symptoms).
- Outcome: Not all dogs with DCM will improve and improvements in the echocardiogram, when they do occur, can take a long time (often more than 6 months).
- If my dog is eating a BEG diet but has no symptoms, should I test for DCM or switch to a different diet? It’s unlikely that most dogs eating a BEG diet will develop DCM. However, given the fact that we don’t yet understand why BEG diets are affecting some dogs and because DCM is a life-threatening disease, I recommend you reconsider your dog’s diet until we know more. Contrary to popular belief, there are no health benefits of grain-free or exotic ingredient diets except in the rare case of food allergy. If your dog is a part of your family and you want to feed him the very best, be sure to base this important decision on more objective factors than marketing and the ingredient list (see our post).
Be sure to watch for early signs of heart disease – weakness, slowing down, less able to exercise, shortness of breath, coughing, or fainting. If you notice any of these, get your dog checked out by your veterinarian who will listen for a heart murmur or abnormal heart rhythm (although not all dogs with DCM have any changes that can be heard with a stethoscope). Your veterinarian (or a veterinary cardiologist) may do additional tests, such as x-rays, blood tests, electrocardiogram, and ultrasound of the heart (echocardiogram – the test of choice to diagnose DCM).Tell your veterinarian what you’re feeding your dog. You can help your veterinarian by bringing a list of everything your dog eats to every appointment.
If your dog has no symptoms, additional testing is really up to you. Some owners have measured plasma and whole blood taurine levels or scheduled an echocardiogram to check their dog’s heart size and function. However, given the cost of an echocardiogram, other owners have elected to have their veterinarian do a blood test called NT-proBNP, which goes up when the heart is enlarged. While a normal value doesn’t guarantee your dog has no heart disease, a high level suggests your dog’s heart should be evaluated further.
- Has diet-associated DCM been seen in cats? The association between BEG diets and heart disease has only been reported in dogs so far. However, that doesn’t mean cats are immune. If your cat is diagnosed with DCM and is eating a BEG, vegetarian, vegan, or home-prepared diet, I recommend following the same protocol as described for dogs with DCM.
Lastly, if your dog has been eating a BEG diet and has been diagnosed with DCM, please don’t feel guilty. I’ve talked to owners who feel terrible because they wanted to provide the finest care for their dog by feeding them the best diet possible. They often spent a lot of money buying an expensive boutique diet and now that same diet may be associated with their dog’s heart disease. Trying to decide what is really the best food is confusing and difficult because of the many different products available, nutrition fads, and compelling marketing. My hope is that the one bright side of this serious situation is that it will shine a light on the complexities of making safe and nutritious pet food and the importance of nutritional expertise and quality control, rather than just what is new and trendy.
For more information about heart disease in dogs, please see our HeartSmart website.