Everything You Need to Know About Dilated Cardiomyopathy (DCM) in Dogs


Everything You Need to Know About Dilated Cardiomyopathy (DCM) in Dogs

A big heart can mean lots of love—but maybe a serious heart problem, too. JoAnna Pendergrass, DVM head shot
JoAnna Pendergrass, DVM head shot By JoAnna Pendergrass, DVM September 28, 2022 Advertisement Pin FB More Tweet Email Send Text Message Print woman sitting with her Great Dane in her contemporary living room; dilated cardiomyopathy in dogs
woman sitting with her Great Dane in her contemporary living room; dilated cardiomyopathy in dogs Credit: andresr / Getty

On This Page

  • What is DCM in Dogs?
  • Causes
  • Symptoms
  • Diagnosing
  • Treatment
  • Prognosis
  • Prevention

Day and night, a dog's heart works hard to pump blood throughout the body and give your dog the ability to run, jump, play, and snuggle. However, heart conditions such as dilated cardiomyopathy (DCM) make it harder for the heart to function correctly.

DCM in dogs is a progressive, irreversible heart disease that requires constant management and monitoring to give affected dogs the best possible quality of life. Here, we discuss the causes, symptoms, treatment, and more of this disease.

What is DCM in Dogs?

DCM in dogs is a weakening of the heart muscles, leading to an inability of the heart to contract and pump blood efficiently. Weak heart muscles also cause a thinning of the heart chamber walls and eventual heart chamber enlargement.

When the heart cannot pump blood well, blood backs up in the heart, increasing blood pressure. Increased blood pressure damages the heart valves, which separate the heart chambers and keep blood flowing properly through the heart.

DCM most commonly affects the left side of the heart, leading to a backup of blood in the lungs. The lungs' blood vessels become leaky, causing pulmonary edema. Less commonly, DCM can affect the right side of the heart.

DCM typically affects middle-aged and senior dogs and is most commonly seen in large and giant breed dogs.

RELATED: 6 Things Every Pet Owner Should Know About Heart Disease in Dogs

What are the Causes of DCM in Dogs?

In many cases of DCM, the cause is unfortunately unknown, but we do know that genetics plays a role in DCM development. Several large and giant breeds and a few smaller breeds are genetically predisposed to developing DCM, including:

  • Boxer
  • Great Dane
  • Newfoundland
  • German shepherd
  • Doberman pinscher
  • Labrador retriever
  • Cocker spaniel

Nutritional deficiencies of taurine and l-carnitine, as well as toxins and infection, can also contribute to DCM.

Additionally, grain-free diets may be linked to DCM. Several years ago, veterinary cardiologists began detecting DCM in dogs not genetically predisposed to the disease. What these dogs had in common was consuming a grain-free diet, which contains ingredients like peas, lentils, potatoes, or beans instead of rice, corn, barley, wheat, or other grains. Since that time, the FDA has been investigating this potential link, but the findings are not yet conclusive.

What are the Signs and Symptoms of DCM in Dogs?

Dogs have few, if any, symptoms during the early stage of DCM. A dog with early-stage DCM may have exercise intolerance, but this is not specific to DCM. As the disease progresses, though, signs and symptoms develop rapidly. These signs are typically the same as those for left-sided congestive heart failure (CHF), including:

  • Fainting
  • Lethargy
  • Weakness
  • Sudden collapse
  • Rapid, difficult breathing
  • Coughing (enlarged heart presses on the trachea)

Dogs with later-stage DCM may also have a reduced appetite and swollen belly.

Diagnosis of DCM in Dogs

Because DCM is not easily detectable early on, it is usually not diagnosed until signs of CHF are present. Diagnosing DCM in dogs involves a physical exam, X-rays, and heart tests.

During the physical exam, your veterinarian will listen to the heart for arrhythmias (abnormal heart rhythm). Listening to the lungs may reveal congestion, indicating pulmonary edema. Other physical exam findings may include a swollen jugular vein and abdomen.

Chest X-rays allow your veterinarian to look at your dog's lungs and heart. If your dog has DCM, the lungs will look fluid-filled and the left side of the heart will be enlarged and possibly pressed against the trachea.

Abdominal X-rays, if taken, may show a fluid-filled abdomen, called ascites.

Electrocardiography and echocardiography are the heart tests used to diagnose DCM. An electrocardiogram measures the heart's rate and rhythm and identifies arrhythmias. An echocardiogram is a heart ultrasound that measures how well the heart can pump blood.

Basic bloodwork provides information about your dog's overall health, including liver and kidney function. If your veterinarian suspects a taurine deficiency, they will perform a blood test to measure taurine levels.

How to Treat DCM in Dogs

Sadly, DCM is irreversible and incurable. Therefore, treatment is aimed at reducing symptoms and slowing disease progression. Your veterinarian will develop a personalized treatment plan according to your dog's overall health and underlying health condition, if present.

Removing excessive fluid is critical when treating DCM. Although diuretics are very effective, severe fluid buildup often requires periodic, manual fluid removal from the lungs (thoracocentesis) or abdomen (abdominocentesis).

Various medications, such as angiotensin-converting enzyme inhibitors and anti-arrhythmia medications, help promote heart function and slow disease progression. For dogs with taurine or l-carnitine deficiencies, nutritional supplementation may be recommended. However, supplementation does not guarantee improvement of DCM symptoms.

At home, you will need to monitor your dog's symptoms. Contact your veterinarian if the symptoms worsen. Follow-up appointments are necessary to monitor your dog's symptoms and response to treatment. Your veterinarian will perform X-rays, blood pressure testing, heart tests, and bloodwork during these appointments.

What Is the Prognosis for Dogs with DCM?

The prognosis for dogs with DCM varies and depends on the stage of the disease at diagnosis.

Dogs with CHF at the time of a DCM diagnosis have a poor prognosis, with a life expectancy between 6 and 24 months after their diagnosis.

Dogs with DCM that have not yet developed CHF could enjoy a good quality of life for several years with proper disease management. However, these dogs will eventually develop signs of DCM and CHF.

How to Prevent DCM in Dogs

Unfortunately, DCM in dogs is not generally preventable. It's important to take your dog to the vet for yearly wellness exams, plus anytime you think something might be amiss. Talk to your vet about the healthiest diet options in order to avoid nutritional causes of DCM.

In addition to regular vet care, you can learn how to conduct an at-home health checkup for your pet to help give you a baseline for comparison when you think something might be up. This is the best chance for early detection of DCM and other health conditions.

Responsible dog breeders often screen dogs with a genetic predisposition to DCM prior to breeding. If you plan to get a dog from a breeder, ask about their heart disease screening practices, especially if the breed is known to be prone to DCM or another heart disease.

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