Canine heart disease from unusual diets: More than a grain-free issue!

Since 2017, veterinarians started to notice more dogs developing severe heart muscle disease than they had ever seen before. All around the country, both owners and veterinarians were surprised and saddened by this increase. The disease is called dilated cardiomyopathy (DCM) and is usually seen in large breed dogs.  Lately though, smaller breed dogs and many types of breeds not expected to get DCM are being diagnosed in higher numbers. The most common thing these dogs share is being fed a non-traditional diet, often, but not always, grain-free. Once the diet is switched, many pets’ heart function will improve. The FDA started collecting data on these cases and in 2018, sent out an alert making the connection between these new cases and certain diets, e.g, grain-free diets or grain-containing diets high in peas, lentils, and/or potatoes. The condition is now called Diet Associated DCM. Since then, many researchers and veterinarians continue to work hard to better understand the problem.  We have learned a lot, but there is still much we do not understand.

What is dilated cardiomyopathy (DCM)?

DCM is a disease that causes the heart muscle to weaken. In many cases, it causes heart failure and even death. Most of the time, it is genetic based and most common in high risk breeds such as the Doberman Pinscher, Boxer, and Great Dane. Prior to now, there were uncommon cases of  DCM that arose from lack of certain nutrients in the diet and rarely from toxins or infections. The recent connection between certain diets and the increased cases of DCM suggests a diet related cause even though scientists still do not know exactly how or why the disease develops in some dogs and not others.

What are the symptoms?

In the early stages, dogs do not show symptoms. However, as the disease worsens it can cause weakness, lagging on walks, loss of interest in play, coughing, breathing problems, fainting, and even sudden death.

Is it just a grain-free issue? (Spoiler alert: No!)

There is a misconception that this problem is only seen in dogs on “grain-free diets” and that the lack of grain is the issue. This is not the case. The culprit does not appear to be a lack of grain, but instead a high level of legumes, e.g., lentils, peas, chickpeas, beans, pea fiber, pea starch, other pulses, and possibly potatoes. Potatoes were initially thought to be a concern, but this is likely no longer the case.  It is important to note that there are some grain-containing diets that are high in their content of legumes and potatoes that may have been linked to Diet-Associated Cardiomyopathy (DA-DCM). Supplementing grains, such as rice, to your dog’s grain-free diet will not avoid problems. Instead, avoid diets high in legumes. Even if your dog’s diet is not “grain-free,” check the label for these ingredients to better understand the risk the diet may pose to your dog. Exactly how these ingredients may contribute to DCM is still unknown.   

A link to some of the diets from the FDA study can be found here.  https://www.fda.gov/animal-veterinary/outbreaks-and-advisories/fda-investigation-potential-link-between-certain-diets-and-canine-dilated-cardiomyopathy#diet

What’s the role of taurine in DCM?

Animals need taurine in their diet to maintain the strength of their heart muscle. If they don’t get enough taurine, both dogs and cats can develop DCM. Because this has been proven before, lack of taurine was thought to be the cause of these new cases. However, studies showed that most of the DA-DCM dogs have normal taurine levels (90% in a recent study). Even though lack of taurine is not the problem in most of these cases, it may play a small role in certain breeds - such as Golden Retrievers, American Cocker Spaniels, Newfoundlands, and others.

What’s the treatment for DA-DCM?

If caught early, diet change may be all that is needed. Dogs that are eating a nontraditional diet that is high in legumes and are changed to a traditional diet will usually have improved prognosis and survival time.  With more advanced disease, several medicines are needed to help boost heart function, treat fluid build-up, and improve the heart rhythm. Many of the medications used to treat this disorder are used for heart disease in people in addition to other veterinary specific medications like Vetmedin (pimobendan).

What is the outlook for DCM patients?

Good news! Unlike the DCM that is seen in lines of large breed dogs, DA-DCM can be reversible if it is caught early in the course of the disease. By switching to a traditional diet, many dogs get a lot better and can even return to normal - although it can take up to a year or more after being on the new diet. Sadly, in more advanced cases, the damage to the heart can be permanent. Changing the diet and starting heart medications may improve heart function and survival, but these patients' lives are shorter because of this terrible disease.

Are certain breeds more likely to be affected by DA-DCM?

Although DA-DCM can occur in any breed, there is some concern about an increased risk of nutritional related DCM in the Golden Retriever, Pit Bulls, Labrador Retrievers, and possibly some Doodle breeds.

Are cats affected?

Although uncommon in cats, there have been a few reported cases of cats on high-legume/potato diets that developed DCM. In addition, cats on homemade, vegetarian, or vegan diets are at increased risk of taurine-deficient DCM.

What should I do if my pet has been on one of these diets but has no symptoms?

Don’t panic! Most dogs on these diets do not develop DCM, although recent studies suggest that many dogs on these diets may have mild changes to the heart that resolve with a change in diet. The longer a pet is on these diets, the higher the risk of problems. 

•         Consider switching to a more traditional diet to avoid problems. If your pet has specific needs, such as food allergies, talk to your veterinarian about options for diets or consider working with a board certified veterinary nutritionist.
•         Schedule a visit with your vet so they can check for abnormal heart sounds or a rhythm problem or other signs of heart disease
•         If your pet is normal at home and your vet does not have any concerns,  further testing for DCM is up to you. An echocardiogram with a veterinary heart specialist (veterinary cardiologist) is the best way to check for DCM, but it can be expensive. Other tests, such as an NT-proBNP blood test or X-rays of the heart and lungs are also options to help screen for disease. 

What should I consider when choosing pet food?

There is no single perfect diet for all pets. Check with your veterinarian to help figure out which diet is best for your pet.

•         Any diet change should be done gradually over a few weeks to avoid stomach upset.
•         Consider foods made by companies with veterinary nutritionists on staff and long histories of producing high quality diets. Diets that have been feed trial tested by the Association of American Feed Control Officials (AAFCO) are ideal. A few companies that meet these high standards and would be good choices include Science Diet, Royal Canin, Purina, and Iams.
•         Avoid diets that have legumes or their parts/fractions, e.g., pea fiber/pea starch, etc., in the first 5 -10 ingredients. Or, better yet, find diets without these ingredients altogether.
•         Be cautious of diets with exotic proteins, low protein levels or high fiber since these have been linked to taurine deficiency.
•         If feeding a vegetarian, vegan or home-cooked diet, it is best to meet with a board-certified veterinary  nutritionist to be sure the diet is meeting all the needs of the pet. 

References

1. Freeman LM, Stern JA, Fries R, et al. Diet-associated dilated cardiomyopathy in dogs: what do we know? JAVMA 2018; 253l 1390-1394.
2. USFDA.FDA investigating potential connections between diet and cases of canine heart disease. Jul 12, 2018. Available at www.fda.gov/Animalveterinary/NewsEvents/CVMUpdates/ucm813305.htm
3. Freeman LM. A broken heart: risk of heart disease in boutique or grain-free diets and exotic ingredients. Jun 4,2018. Available at vetnutrition.tufts.edu/2018/06/a-broken-heart-risk-of-heart-disease-in-boutique-or-grain-free-diets-and-exotic-ingredients/
4. USFDA.Vet-LIRN Update on Investigation into Dilated Cardiomyopathy. June 27, 2019. Available at www.fda.gov/animal-veterinary/science-research/vet-lirn-update-investigation-dilated -cardiomyopathy.
5. Diet-Associated Dilated Cardiomyopathy (DCM): Update July, 2019. Available at https://vetnutrition.tufts.edu/2019/07/dcmupdate/
6. S.I.Karp, BA L.M.Freeman, DVM, PhD. J.E.Rush, DVM, MS W.G. Arsenault, DVM, et al. Dilated cardiomyopathy in cats: survey of veterinary cardiologists and retrospective evaluation of a possible association with diet 
   https://www.sciencedirect.com/science/article/abs/pii/S1760273421001259#!