Dilated Cardiomyopathy in Dogs

Causes, Treatment, and Prevention

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Dilated cardiomyopathy (DCM) affects a dog's heart, enlarging the chambers and weakening the walls so that the heart cannot function normally. Symptoms are nonspecific early in the disease and may include lethargy, labored breathing, and weight loss. A veterinary evaluation is necessary to achieve a diagnosis, and then the condition may be managed with dietary changes and medication. Untreated, DCM can lead to heart failure. Some dog breeds are predisposed to developing dilated cardiomyopathy but it can occur in any breed.

What Is Dilated Cardiomyopathy?

Dilated cardiomyopathy occurs when a dog's heart chambers become dilated (enlarged). A dog has four chambers in its heart, and if these chambers become dilated they will be unable to efficiently pump blood. The chamber walls become thin, and the valves within the heart that control the direction of blood flow may leak. This can eventually lead to congestive heart failure.

Symptoms of Dilated Cardiomyopathy in Dogs

Since it affects an internal organ, DCM is not a disease you can see, but you can look for signs and symptoms of heart issues in your dog. These may include one or more of the following symptoms:


  • Lethargy
  • Difficulty breathing
  • Collapse/fainting
  • Coughing
  • Weakness
  • Weight loss
  • Loss of appetite
  • Increased respiratory rate
  • Bloated abdomen

Dilated cardiomyopathy affects how much oxygenated blood flows through the body, so the first signs of the disease may be generalized weakness and lethargy. Next, there may be difficulty breathing, an increase in your dog's respiratory rate, and coughing.

Weight loss will occur over time since your dog doesn't have much of an appetite and you may see your dog's belly become bloated due to fluid accumulation.

Fainting or collapse can occur if your dog is unable to breathe well enough or if the disease progresses without treatment.

Causes of Dilated Cardiomyopathy

While some cases of dilated cardiomyopathy occur for no apparent reason, certain factors predispose dogs to this disease. These causes include:

  • Nutrition: Dogs that are eating grain-free diets with exotic ingredients or home-cooked diets are susceptible to developing DCM. While the exact cause of DCM in these dogs is still unknown, some dogs will have low taurine levels or are thought to be unable to properly absorb taurine due to the diets they are consuming. Research is ongoing.
  • Infection/Toxins: While rare, drugs like doxorubicin, viruses like parvovirus, and infections like Chagas disease can cause DCM in dogs.
  • Genetics: Certain dog breeds have an inherited predisposition to developing DCM. A genetic component has been found in these breeds. Dog breeds that are suspected to be at a higher risk for developing DCM include Cocker spaniels, Doberman pinschers, Great Danes, boxers, Irish wolfhounds (especially males), and Portuguese water dogs.

Diagnosing Dilated Cardiomyopathy in Dogs

Your veterinarian will listen to your dog's heart and lungs to gather preliminary information such as heart and respiratory rate, the presence of a heart murmur, and lung sounds.

If DCM is suspected, X-rays will be recommended to assess the lungs and heart and to see if any fluid is accumulating. An echocardiogram, or ultrasound of the heart, will then be needed to see how well the blood is being pumped through the heart, the heart chambers' size, and assess the heart valves.

Finally, an EKG, or electrocardiogram, will evaluate the heart's rhythm to see if an arrhythmia is present.


If a nutritional cause is suspected, your vet will recommend a dietary change to ameliorate the effects of questionable ingredients or taurine deficiency. If an infection is the cause of the DCM, treatment of the underlying disease will be necessary in addition to heart disease treatment.

For genetic causes of DCM, treatment of heart disease is the only option. Medications, diet, and supplements to support the heart's ability to function and decrease fluid build-up can be helpful.

Prognosis for Dogs with Dilated Cardiomyopathy

When detected early, DCM can usually be managed with targeted treatment strategies. Advanced cases are more likely to suffer heart failure even with supportive treatments.

How to Prevent Dilated Cardiomyopathy

Dogs with a familial history of DCM should not be bred. While this does not guarantee that their offspring won't one day develop this disease, it will decrease the likelihood of it occurring.

Additionally, grain-free diets are not recommended due to the purported link they have with DCM in breeds that are traditionally not affected by this heart problem.

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  1. Unusual Cases of Canine Heart Disease DCM Linked to Boutique Diets. University of Illinois College of Veterinary Medicine.