Veterinarians worldwide are seeing an increase in dilated cardiomyopathy in dogs not previously disposed to this condition. Dilated cardiomyopathy (DCM) is a condition that causes the heart muscles to become enlarged and weakened. So what is the one common factor? A grain-free diet that is based on unconventional ingredients.

DCM is typically seen in large breed dogs such as Great Danes, St. Bernards, Boxers, and Mastiffs – to name a few. More recent cases, however, have included smaller breed dogs such as Boston Terriers, Yorkies, and Pomeranians.

Dr. Ryan Fries, a board-certified cardiologist at the University of Illinois Veterinary Teaching Hospital in Urbana, IL, performed a recent study on grain-free diets and dogs being diagnosed with DCM. Dr. Fries and his research team found a correlation in pets being fed uncommon diets and unusual sources of protein that are not frequently used in dog foods.

Growing concern has multiple institutions, including the University of Illinois and the Food and Drug Administration, attempting to identify a reason as to why these particular diets would cause heart issues in our pets. Despite running multiple tests, they have yet to identify a specific deficiency of an essential vitamin, mineral or amino acid. There has also been no specific cardiac toxin identified. While they unfortunately do not know what exactly is causing the the negative cardiac effects yet; one of the factors that appear to play a key role is the size and experience of the pet-food manufacturer.

Boutique diets tend to come from much smaller manufacturers that may lack the proper nutritional expertise and resources to ensure quality control that larger, more established companies have on their teams. (I.e. Hill’s, Royal Canin, Iams, Purina, Natural Balance, etc.). There has also been multiple cases of dogs developing DCM after being fed home-cooked diets. Researchers, however, have not seen a rise in DCM in small breed dogs that are on grain-free diets from large manufacturers such as the ones listed above.

A similar rise in DCM developed in cats during the 1980’s. That issue was later linked to commercial pet foods being deficient in taurine, an amino acid found in animal protein. Many veterinarians and researchers initially thought the current case of DCM in dogs may be due to a taurine deficiency. While low taurine levels have been documented in some dogs, nutritional analyses of the suspected diets and many other dogs have shown adequate levels.

Dr. Fries suspects that there may be potential for some unknown component (or lack thereof) that could be affecting dogs’ ability to absorb and use the taurine. Recent studies by the FDA show there is a possible link to peas and other legumes, which are often used as a key ingredient in grain-free diets. Researchers are currently exploring these options. While taurine deficiency is reversible with proper diet change and supplementation, most dogs are already in heart failure by the time DCM is diagnosed.

There is still more research that needs to be done. However, researchers have established the link between grain-free diets from boutique manufacturers and dilated cardiomyopathy in our canine patients. If you are feeding your dog a grain-free diet, regardless of the manufacturer, talk to your veterinarian about potentially switching to another diet and scheduling your dog for a heart evaluation.