Grain-Free Diets and Dilated Cardiomyopathy

We have had many clients ask about the recent correlation with grain-free diets causing dilated cardiomyopathy (or DCM) in dogs. DCM is a heart condition that causes the ventricles to increase in size, and the heart muscle to decrease in size, and anatomically changes the shape of the heart. These deteriorations can cause the heart to not pump as well, leading to congestive heart failure. Here is what we know:

1. Grain-free diets for domesticated dogs and cats is not necessary. Most people switch their pets to grain-free diets based on the thought that when they have a food allergy, the animal is allergic to the grain like a human would be. It is very uncommon that a pet is allergic to a grain; 98% of the time the allergy is to a protein source (the top two allergens are chicken and beef). When there is a food allergy, we usually recommend switching the protein source to a novel protein (such as rabbit, turkey, or bison), or switching to a prescription hydrolyzed protein diet.
2. It’s not just grain free diets- the red flags are coming from what is being classified as BEG diets; “boutique brands”, exotic formulas, and/or grain-free formulas1. The linkage may be between grain replacements such as legumes (lentils, chickpeas), but can also be due to exotic protein sources such as alligator and ostrich1. A “boutique brand” is any food made from a smaller pet food company. 3. The most recent discovery is a correlation between Taurine deficiency causing DCM1,2. Taurine is an amino acid that is involved with preventing swelling of the heart muscles and cells by attracting water when/where it is needed3. Too much or too little water can cause the heart cells to shrink or swell and burst
3. The association of grain-free diets and Taurine is that the legumes that are replacing the grain in the formulas do not supply enough Taurine.
4. Most dogs diagnosed with DCM do not have low Taurine levels, however dogs with normal Taurine levels and diagnosed DCM have shown improvement when their diet is switched1,2. This indicates that there is an additional factor playing a role. Supplementing Taurine separately is not a sufficient alternative.
5. Diet associated DCM with taurine deficiency is the least common form of DCM seen currently, and is not associated with DCM cases in pre-disposed breeds1.
6. A raw or home-cooked diet is not a safe alternative1. These types of diets expose your pet to other potential health complications such as Salmonella or a plethora of illnesses due to a nutritionally unbalanced diet.
7. The diet-associated DCM is more commonly seen in large breed dogs such as Retrievers and Shepherds (not limited to those breeds)1,2.
8. Diet-associated DCM has only been reported in dogs thus far1. However, that does not mean cats are in the clear. DCM is an uncommon disease in cats, and if your cat is diagnosed and is on a BEG diet, the same treatment would be indicated. A more common heart disease in cats is called hypertrophic cardiomyopathy (HCM), which the heart muscles become abnormally thickened. This too can be the result of a Taurine deficient diet.

The research on this topic is in very early stages and very little is definitively known. Due to the fluctuation in the collected data, we cannot say for sure what is causing the disease. Our recommendation at this point is to refrain from feeding your pet a grain-free diet. PLEASE be cautious in choosing your pet's food as a lot of brands have a mixed selection of normal and grain-free formulas, as well as good advertising techniques. Brands such as Nutro, Fromm, Natural Balance, and Wellness are great brands, but do have a plethora of grain-free formulas. The AVMA recommends that we steer clear from grain-free treats as well.

Lastly, we ask that you not panic if your pet is on a grain-free diet and do not rely on Dr. Google for your source of information. As stated, this research is in the very early stages and not a lot is definitively known. We recommend switching the food based on the potential for health complications. We will keep everyone updated as more research emerges. 

References

Freeman DVM, L. It’s Not Just Grain-Free: An Update on Diet-Associated Dilated Cardiomyopathy. Cummings Veterinary Medical Center at the University of Tufts. http://vetnutrition.tufts.edu/2018/11/dcm-update/. Published November 28, 2019.

Freeman DVM, L. Stern DVM, JA. Fries DVM, R. Adin DVM, DB. Rush DVM, JE. Diet-Associated Cardiomyopathy in Dogs: What Do We Know? Journal of the American Veterinary Association. 2018 Dec 1; 253(11): 1390-1394.

Reines DVM, BP. Grain-Free take-home message: “GO SLOW, BE CONSERVATIVE!” Presented from: St. Francis Animal Hospital, North Huntington, PA.