Diet-Related Dilated Cardiomyopathy In Dogs

By Teresa Garden, DVM

Dilated cardiomyopathy (DCM) is a heart disease usually found only in certain breeds of dogs due to genetic risk factors. Breeds at risk for DCM are Doberman Pinschers, Boxers, Irish Wolfhounds, and Great Danes. Surprisingly, veterinary cardiologists from all over North America began seeing this disease in all types of dogs beginning in January 2014 and continuing to present day. Some cardiologists were seeing DCM in multiple dogs from the same household. To date, over 500 dogs of various breeds and mixes have been diagnosed. The FDA launched an official investigation into this matter beginning in July 2018. Veterinarians, nutritionists, pathologists, and epidemiologists are collaborating with several sections of the animal health world to collect and evaluate information about the DCM cases. The investigation has consisted of reviews of medical records and performing dietary and environmental exposure interviews. This part of the investigation uncovered the fact that 93% of these new cases seemed to have one thing in common- the dogs were eating grain-free kibable containing peas, lentils, potatoes, and other legumes. Observant veterinary cardiologists then raised the concern that certain diets may cause or exacerbate DCM in some dogs.

The following is a list of the grain-free kibble brands of dog food and the number of cases of DCM dogs out of the 515 dogs studied thus far: Acana (67), Zignature (64), Taste of the Wild (53), 4Health (32), Earthborn Holistic (32), Blue Buffalo (31), Nature’s Domain (29), Fromm (24), Merrick (16), California Natural (15), Natural Balance (15), Orijen (12), Nature’s Variety ((11), NutriSource (10), Nutro (10), and Rachel Ray (10). Grain-free foods have been around for about 20 years. Why is this problem showing up now? One answer may be taurine-deficiency.

Taurine is an amino acid found in animal-based proteins such as meat, fish, and eggs. It is not found in plant-based protein sources. Taurine helps to build protein and it is required for proper function of muscle tissues-especially the heart, eyes, and brain. Dogs are generally able to make taurine from other amino acids found in their diet. It is well known that a taurine-deficiency can lead to DCM. Some dogs in the FDA study were found to be deficient in taurine. Some of these dogs got better with taurine supplementation and heart medications used to treat DCM. Some of the dogs in the study did not have low taurine levels. However, when their diets were changed, they got better. Some of the new diets contained grains and some were grain-free.

This research showed that a lack of grains alone is probably not the cause of diet-related DCM. The research found most of the dogs were consuming fewer calories than recommended. This suggests daily caloric intake could be a contributing factor to DCM. Another factor to consider is that these particular diets may be unbalanced. Low quality grain-free foods have high concentration of plant-based proteins such as lentils, peas, potatoes, and other legumes. Could these types of diets be deficient in some other essential nutrients besides taurine that may put the dog at greater risk for DCM? The formulation of a particular diet is crucial in order to meet and exceed the basic nutritional requirements of dogs. Not all manufacturers have the same level of nutritional expertise and quality control and that variability could introduce potential nutritional deficiencies with some products.

How these diets are processed may also play a role in dietary DCM. High temperatures used in processing dog food may alter the bioavailability of taurine and other nutrients. High temperatures create pro-inflammatory mediators leading to inflammation in the GI tract and the body. Microbes can be altered by chronic inflammation in the gut caused by IBD, cancer, or consuming dog food processed at high temperatures. If microbes in the gut are out of balance it creates an environment that favors bacteria that degrade taurine.
Could other nutrients be affected in this way as well?

As of this writing, we can say for sure there is a dietary factor harming the hearts of our dogs. But is it a nutrient excess or deficiency? Is it a toxicity? Is it the processing? Is it the quality or sourcing of ingredients? We have more questions than answers leading to frustration in pet owners and their veterinarians. We know more now than we did a year ago. I’m sure we’ll know more in the future.

In the meantime, if your dog has been eating one of the implicated brands of food mentioned above, it may be prudent to have your veterinarian screen your dog for DCM. This can be done with a chest radiograph and a blood test called a CardioPro BNP level. Your dog may not show any symptoms yet could have DCM. An echocardiogram performed by a veterinary cardiologist is needed to confirm DCM. Watch for any signs of heart disease-weakness, slowing down, exercise intolerance, panting, coughing, and fainting. And, most important, stop feeding the specific dog food brands of grain-free kibble mentioned above.

For all of us, trying to decide what is really the best food for our pet is very confusing and difficult. There are hundreds of products, nutritional fads, and competing marketing that can boggle the minds of consumers. Pet food companies would be well served by employing the expertise of veterinary nutritionists when formulating their products rather than relying on slick marketing campaigns to sell them. Our faithful companions would be better served as well.

Dr. Teresa Garden is chief veterinarian/owner of Animal Health & Healing, a full-service holistic and conventional veterinary practice in the Maplewood/Richmond Heights area. 314-781-1738.