Dilated cardiomyopathy (DCM) is a specific heart condition characterized by dilated heart chambers, a thin heart muscle,  and decreased contractility (decreased ability of the heart muscle to contract), which results in decreased ability of the heart to pump blood throughout the body. 

Unfortunately, there is no cure for DCM.  Treatment is aimed at controlling symptoms and delaying the onset of heart failure.

What is dilated cardiomyopathy?

• Dilated cardiomyopathy (DCM) is a specific heart condition characterized by dilated heart chambers, a thin heart muscle,  and decreased contractility (decreased ability of the heart muscle to contract), which results in decreased ability of the heart to pump blood throughout the body.  The cause of DCM is usually unknown; rarely, it is due to a nutritional deficiency such as Taurine.  DCM is a heritable condition that is seen most frequently in large breed dogs such as Doberman Pinschers, Irish wolfhounds, Great Danes, Boxers, and Newfoundlands.

Clinical Signs

• Early signs may include fainting, exercise intolerance, weight loss or lethargy.  Many dogs will remain asymptomatic, and will suddenly have symptoms associated with heart failure.  Signs associated with heart failure include respiratory distress from left heart failure, or abdominal distention from fluid build-up associated with right heart failure.  The onset of symptoms may be extremely rapid.  It is not uncommon for dogs to have a history of symptoms of only a few days duration.
  

Diagnosis

• Diagnosis can be made by a combination of the following diagnostic tools:
  • Auscultation – certain sounds heard while listening to the heart and lungs with a stethoscope can be suggestive of DCM and heart failure
    
  • Chest x-rays – the heart may be enlarged, or opacities may be noted in the lungs suggesting pulmonary edema (fluid in the lungs) associated with heart failure. Some dogs (especially Doberman Pinschers) may have normal appearing x-rays.
    
  • ECG (electrocardiogram) – cardiac arrhythmias (irregular heart rhythm) are frequently seen.
    
  • Echocardiogram (ultrasound of the heart) – heart chamber dilation is noted, as is decreased ability of the heart muscle to contract. 

Treatment

• Unfortunately, there is no cure for DCM.  Treatment is aimed at controlling symptoms and delaying the onset of heart failure.
• Dogs that present to the veterinarian in heart failure are treated with oxygen therapy and Furosemide (Lasix – a diuretic to decrease fluid accumulation in the lungs).
• Dogs may be treated at home with a combination of the following medications:
  1. Furosemide (Lasix) – A low, maintenance dose of Lasix is given orally to promote diuresis (urinating excess fluid).  Excess fluid in the blood vessels may lead to pulmonary edema (fluid in the lungs).  Kidney values should be monitored while on this medication.
  2. ACE inhibitors (Enalapril) – This medication helps delay the onset of heart failure by a number of mechanisms.  Kidney values should be monitored while on this medication.
     
  3. Digoxin – This medication may be used to help improve contractility of the heart, or to help control arrhythmias
     
  4. Calcium channel blockers and Beta blockers – These medications are used to help control cardiac arrhythmias.
     
  5. Nutritional supplementation with Taurine, L-Carnitine, and Coenzyme Q-10 may be beneficial; however, the effects of these supplements on canine DCM have not been proven.

Potential Complications

• Because there is no cure for DCM, most dogs with DCM will die from heart failure or arrhythmias that are not responsive to treatment, or euthanasia due to the poor prognosis.

Prognosis

• Prognosis for long term survival is poor.  The probability of one-year survival is from 17-37 percent.  Some dogs may respond well to initial therapy and can live for months (common) to years (rare).  Other dogs do not respond to initial therapy and may be euthanized or die within the first few days of diagnosis.  Unfortunately, there is no way to predict how an individual dog will respond.

References

• Abbott, Jonathan. Medical Management of Dilated Cardiomyopathy. ACVIM 2003 Proceedings. Ettinger, Stephen and Edward Feldman. Textbook of Veterinary Internal Medicine, Volume 1, 2000.