Dilated Cardiomyopathy in Large Dogs: Predisposed Breeds, Symptoms, and Treatment Methods

Unlike small dogs prone to valvular diseases, large dogs are more susceptible to a condition known as dilated cardiomyopathy (DCM). DCM is more common in purebred dogs and is usually hereditary, such as Labrador Retrievers, Golden Retrievers, Doberman Pinschers, and so on. Other causes of dilated cardiomyopathy include nutritional issues, endocrine problems, or inflammation and infections. Dilated cardiomyopathy leads to a decrease in the heart’s contractility, dilation of the ventricles and atria, and subsequently causes serious heart failure, arrhythmias, and a decline in exercise capacity in dogs.

In recent years, the popularity of grain-free diets has raised concerns about their potential to increase the risk of dilated cardiomyopathy, and the correlation between the two will be discussed later.

Which Dog Breeds and Conditions are Prone to Dilated Cardiomyopathy?

Dilated cardiomyopathy (DCM) is relatively more common in breeds such as Doberman Pinschers, Irish Wolfhounds, Great Danes, Boxers, Bulldogs, and Golden Retrievers. Among them, Doberman Pinschers are the most susceptible to this disease, and it is generally recommended that Doberman Pinschers undergo routine checks for potential DCM after the age of 2. The high-incidence age range is typically between 4 to 10 years old. Other potential factors include a deficiency of taurine in nutrition, endocrine diseases (such as hypothyroidism), or issues caused by cardiotoxic drugs.

What Conditions Can Dilated Cardiomyopathy Cause?

Symptoms of potential dilated cardiomyopathy are relatively mild, such as slight heart contractility dysfunction on echocardiograms and occasional arrhythmias on electrocardiograms, but these findings may not be reflected in the clinical presentation of dogs, meaning that the dogs themselves may not show obvious discomfort.

However, severe symptoms may include heart failure, atrial fibrillation, ventricular tachycardia, and so on, which can significantly reduce a dog’s spirit or activity, even causing serious issues like shortness of breath and panting. Some may even be at risk of sudden death.

How to Diagnose?

The gold standard for diagnosing heart disease is usually an echocardiogram. In patients with DCM, insufficient heart contractility and enlargement of the heart chambers can be observed. Of course, it is also crucial to clarify the medical history, understanding the patient’s current dietary habits and the timeline of symptom onset.

What Treatment Methods are There for This Disease?

The most standard treatment for DCM is the timely administration of heart medication, with the inotropic drug pimobendan being the primary treatment option. Numerous studies have shown that the early administration of inotropic drugs when DCM occurs can effectively slow down the progression of the disease and extend survival time.

Concerns and Controversies Regarding Grain-Free Diets and Dilated Cardiomyopathy

At the end of 2018, the American Veterinary Medical Association published an article titled “Diet-associated dilated cardiomyopathy in dogs: what do we know?“, which mainly discusses the association and possibilities between grain-free diets (Boutique, exotic-ingredient, and grain-free. BEG) and canine dilated cardiomyopathy, aiming to raise awareness of this issue. Current research indicates that some breeds of dogs have a genetic predisposition to taurine deficiency-induced dilated cardiomyopathy, such as Golden Retrievers, Labrador Retrievers, American Cocker Spaniels, St. Bernards, etc., all of which are more sensitive to taurine deficiency-induced dilated cardiomyopathy than other breeds. Additionally, these large dogs have been proven to have a slower rate of taurine synthesis compared to small dogs. BEG diets have also been suspected in some studies to have relatively poor protein quality or protein structure damage due to high-temperature processing, resulting in insufficient utilizable amino acid content for dogs.

In the past two years, new research reports have continued to point out that Golden Retrievers continuously consuming BEG have marked taurine deficiency and echocardiograms also show obvious cardiac abnormalities. In fact, not only BEG diets, but also homemade fresh food or even vegetarian diets for large dogs can pose a risk of dilated cardiomyopathy due to insufficient taurine intake.

References

• Adin D, DeFrancesco TC, Keene B, Tou S, Meurs K, Atkins C, Aona B, Kurtz K, Barron L, Saker K. Echocardiographic phenotype of canine dilated cardiomyopathy differs based on diet type. J Vet Cardiol. 2019 Feb;21:1-9. doi: 10.1016/j.jvc.2018.11.002. Epub 2018 Dec 5. PMID: 30797439.
• Freeman LM, Stern JA, Fries R, Adin DB, Rush JE. Diet-associated dilated cardiomyopathy in dogs: what do we know? J Am Vet Med Assoc. 2018 Dec 1;253(11):1390-1394. doi: 10.2460/javma.253.11.1390. PMID: 30451613.
• Ontiveros ES, Whelchel BD, Yu J, Kaplan JL, Sharpe AN, Fousse SL, Crofton AE, Fascetti AJ, Stern JA. Development of plasma and whole blood taurine reference ranges and identification of dietary features associated with taurine deficiency and dilated cardiomyopathy in golden retrievers: A prospective, observational study. PLoS One. 2020 May 15;15(5):e0233206. doi: 10.1371/journal.pone.0233206. PMID: 32413894; PMCID: PMC7228784.