Dilated Cardiomyopathy (DCM) in Dogs

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Overview of Canine Dilated Cardiomyopathy (DCM) 

Dilated cardiomyopathy (DCM) is a disease characterized by dilation or enlargement of the heart chambers and markedly reduced contraction. The left ventricle is most always involved. Advanced cases demonstrate dilation of all cardiac chambers.

DCM is very common in dogs, representing the most common reason for congestive heart failure (CHF). This heart disease also can cause heart valve leakage causing heart murmurs or abnormal electrical activity of the heart-producing arrhythmias (irregular or abnormal heartbeats). Large and giant breed dogs, especially males, are predisposed. Doberman pinschers, Irish wolfhounds, Scottish Deerhound, boxer, Afghan hound, Old English Sheepdog, Great Danes, Dalmatians, Newfoundlands, and Saint Bernards are common breeds. English and American cocker spaniel breeds and Portuguese water dogs also develop DCM.

The clinical condition of canine DCM can range from overtly healthy (occult disease) to severe heart failure. Some dogs experience primary electrical disturbances (arrhythmia) such as atrial fibrillation or ventricular tachycardia.

The disease is thought to be genetic in Doberman pinschers, Irish wolfhounds, Newfoundlands, boxers, and Portuguese water dogs. The disease is sometimes seen in Dalmatians fed a low protein diet and in cocker spaniels and gold retrievers with taurine deficiency.

The average age of onset is 4 to 10 years, although Portuguese water dogs can acquire the disease when very young.

DCM is very serious and the mortality rate, even of treated cases, is very high.

What to Watch For

Symptoms of Dilated Cardiomyopathy in dogs may include:  

  • Shortness of breath
  • Coughing
  • Exercise intolerance
  • Collapse
  • Abdominal distension
  • Lethargy
  • Loss of appetite

    The advent of these problems should alert you that a serious emergency is at hand.

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    Diagnosis of Dilated Cardiomyopathy (DCM) in Dogs 

    Diagnostic tests are needed to recognize dilated cardiomyopathy and exclude all other diseases. Tests may include:

  • Complete medical history and physical examination including auscultation of the heart and lungs
  • Thoracic radiographs (chest X-rays)
  • An electrocardiogram (EKG)
  • Arterial blood pressure
  • Packed cell volume test or a complete blood count (CBC)
  • Serum biochemistries, which are blood tests that are especially important if there is heart failure, thromboembolism or complications in other organs
  • Echocardiogram (ultrasound of the heart) to establish the diagnosis and may require referral
  • Treatment of Dilated Cardiomyopathy (DCM) in Dogs 

  • In advanced cases leading to congestive heart failure, drug therapy with a diuretic, angiotensin converting enzyme inhibitor (such as enalapril or benazepril and/or digoxin is prescribed. The diet is changed to reduce sodium intake. Additional drugs may be added such as the diuretic/hormone antagonist, spironolactone. Nutraceuticals such as taurine pills or L-carnitine are recommended in very specific instances.
  • In cases of “arrhythmogenic” dilated cardiomyopathy, drugs that regulate the electrical heart rhythm are indicated.
  • In “occult” dilated cardiomyopathy (healthy dog with early DCM diagnosed by echocardiography), an angiotensin converting enzyme inhibitor drug and possibly a beta-blocker drug is recommended to protect the heart muscle from further damage.
  • Home Care and Prevention

  • Administer any veterinary prescribed medications.
  • Watch for difficulty in breathing, increase in coughing, lethargy or sudden inability to use one or more limbs. Observe the breathing rate when your pet is relaxing.
  • Schedule regular veterinary visits to monitor the condition.
  • In-depth Information on Dilated Cardiomyopathy (DCM) in Dogs 

    Related Symptoms or Diseases

    DCM is thought to be the result of diverse processes that affect heart muscle cell function. The vast majority of cases of DCM are idiopathic, which means they have no known cause and are probably predisposed by genetic factors. Causes may include:

  • Deficiency of metabolic substrates (taurine)
  • Myocarditis (inflammation of the myocardium)
  • Severe global myocardial ischemia (lack of blood supply to the heart)
  • Toxic injury to the heart muscle cells that can be caused by some drugs like doxorubicin or potassium iodide toxicity
  • Persistently abnormal heart rhythms such as sustained ventricular or supraventricular tachycardia
  • Chronic hypokalemia (low blood potassium)
  • Idiopathic

    A number of other diseases can be easily confused with dilated cardiomyopathy unless an appropriate diagnostic evaluation is completed. Diagnostic tests should help exclude the following conditions from consideration:

  • Congenital heart diseases (birth defects)
  • Chronic valve disease
  • Hypertensive heart disease (heart enlargement from high blood pressure)
  • Pericardial diseases (the lining around the heart)
  • Mediastinal masses (tumors in the front part of the chest cavity)
  • Myocarditis (inflammation of the heart muscle – a most difficult condition to diagnose)
  • Moderate to severe anemia (anemia can cause heart failure)
  • Heartworm disease
  • Fever (fever can result in a heart murmur)
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