Dilated Cardiomyopathy (DCM)

Dilated cardiomyopathy is a disease where the heart, for mostly unknown reasons, quits pumping normally and becomes enlarged and flabby.

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Disease Info

Dilated Cardiomyopathy (DCM)

Dilated Cardiomyopathy


  • DEFINITION (What it is):
    • Dilated cardiomyopathy is a disease where the heart, for mostly unknown reasons, quits pumping normally and becomes enlarged and flabby.
  • EPIDEMIOLOGY (Who gets it):
    • Dilated Cardiomyopathy is a disease of large and giant breed dogs, and also affects certain other breeds preferentially and with variations.
      • It is relatively common, seen in about 10% of all canine heart cases
      • These breeds include Doberman Pinschers, Great Danes, Boxers, and American Cocker Spaniels.
        • Doberman Pinschers have a 60% chance of developing DCM at some point
        • It is rare in small breed dogs
      • It occurs in middle aged and older pets
        • It is rare in dogs < 4 years of age
    • It is very rare now in cats due to the addition of Taurine to commercial cat foods.


  • CAUSE:
    • In Doberman pinschers, there are two genes identified, that are passed on in an autosomal dominant fashion
    • Since other breeds can be commonly affected, there is probably a genetic component in them as well
      • Since we don’t know for sure, it is called idiopathic dilated cardiomyopathy
    • In Cocker spaniels, Taurine deficiency has been documented
    • In Boxer DCM, Carnitine deficiency may be relevant
    • There may be other causes in other cases, like viral infection
  • CLINICAL SIGNS:
    • Clinical signs we see
      • None (occult dilated cardiomyopathy)
      • Increased breathing rate (> 30-35 breaths per minute) See our Resting Breathing Rates page
      • Coughing
      • Exercise intolerance or weakness
      • Fainting
      • Sudden death
      • Loss of appetite
      • Weight loss
      • Distended belly
    • Signs are due to two main reasons, the heart muscle becomes weak and flabby, or there are abnormal heart beats present
      • Because the heart is not pumping blood forward effectively, causes blood to back up and force fluid into either the lungs or into body cavities.
        • If the ventricles do not pump blood forward properly, the ventricles and atria get enlarged, and pressure builds up in the left or right atrium. Blood then ‘backs up’, and causes fluid in the lungs or body cavities to accumulate.
          • Fluid in the lungs is called left congestive heart failure (congestion) or pulmonary edema.
            • animals with pulmonary edema breath more rapidly and cough due to the fluid, and cannot exercise well.
          • Fluid in the body cavities is called right congestive heart failure (congestion)
            • Fluid in the chest is called pleural effusion
              • Animals with pleural effusion breath heavily and cannot exercise
            • Fluid in the abdomen is called ascites
              • Animals with ascites often do not eat well
    • Dogs with significant arrhythmias can faint (with exercise or excitement or even at rest), or be at risk for sudden death with a heart attack
  • DIAGNOSIS:
  • Echocardiography
    • An echocardiogram (or heart ultrasound) is used to look within the heart, confirm the diagnosis, and to look for other problems within the heart that might confound therapy.
    • An echocardiogram is the definitive test for diagnosing dilated cardiomyopathy
    • Echocardiograms do not show congestive heart failure, so have some limitations for following the disease.
    • If the disease is in the early stages, where heart size or function is very mildly affected (occult dilated cardiomyopathy)
      • Serial echocardiograms will be necessary
    • Since Choice has all the veterinary and breed normals published to compare values to (through our EchoVet software), we can analyze subtle abnormalities much more carefully


  • Radiography
    • X-rays (radiographs) let us see the heart size (but not inside the heart), and also let us evaluate the lungs (which an echocardiogram cannot perform)
    • Radiographs show how large the heart is in the chest and how it is enlarging with time, and also show congestive heart failure (pulmonary edema) or other lung problems.
    • Radiographs are often repeated with time to assess response to therapy.


  • Electrocardiography
    • An electrocardiogram (EKG or ECG) is very useful to check for rhythm disturbances and may be repeated to assess response to certain medications.


  • Holter Monitor
    • An 24 hour electrocardiogram (Holter monitor) may be required to check for very intermittent rhythm disturbances where we cannot detect significant rhythm disturbances in the office
    • Your pet wears a backpack system at home, and we want you to perform normal activities
    • This is often necessary if a pet is fainting occasionally


  • Blood Pressure
    • A blood pressure is often useful, since the heart is not pumping blood effectively, and blood pressure can be low
    • Some heart medications can lower blood pressure, and cause pets to be weaker on their medications


  • Laboratory Testing
    • Since heart medications can affect other body systems (especially the kidneys), laboratory testing is often essential
    • Labwork is very important, because hearts with disease do not handle water loads very well , but kidneys require water load to maintain function.
    • Usually, there is a wide area to work within where the heart and the kidneys are both happy, but if kidney function is marginal, kidney failure can occur.
    • We may also need to evaluate for other disease that may be making your pet feel ill


  • TREATMENT:
    • Therapy is medical in nature.
      • Heart transplants are not done in animals.
      • The goals of therapy are to maintain your pet out of congestive heart failure for as long as possible on a minimum of medication, for them to feel well and to be playful (although they usually cannot exercise), and for them to eat well.
        • We can affect the heart in a multitude of ways
          • Diuretics (furosemide, spironolactone, hydrochlorthiazide, torsamide)
            • Decrease the amount of fluids that the heart has to handle
          • Inodilators (pimobendan)
            • Make the heart pump blood forward more effectively
          • Vasodilators (amlodipine, benazepril, enalapril, hydralazine, others)
            • decrease blood pressure and make it easier for the heart to pump effectively
          • Hormone system control (benazepril, enalapril, spironolactone)
            • In heart disease, circulating hormones get activated that make the disease progress
              • In some cases, decreasing these circulating hormones can improve survival
          • Rhythm disturbance control (Digoxin, Diltiazem, Mexilitine, Sotalol, others)
            • Since many pets with dilated cardiomyopathy will have significant heart rhythm disturbances, it is not uncommon to have to treat these disturbances
          • Nutritional Supplements (Taurine, Carnitine, Omega 3 Fatty Acids)
            • There are  some nutritional supplements that may be effective in some breeds, such as Taurine or Carnitine.
            • Coenzyme Q has not been shown to be useful in this disease.
          • Diet
            •  See our Food and Diets Information page
              • A severely restricted salt diet such as “Heart diet or H/D” is often not eaten well at all by animals
              • It is more important that your pet eat and eat well, than to stick to the salt restricted diet, even if they won’t eat it.
                • The medications are powerful, and will usually work even if your pet is on regular food.
              • Do not give high salt items such as pork, lunch meats, salted popcorn or high-salt treats.
          • Exercise
            • Exercise is usually moderately restricted
              • They can exercise normally if they want to
              • Restrict the amount or length of exercise
                • Restrict long ball or frisbee throwing, swimming
                • Climbing 14er’s may not be tolerated, and walking in the flats is often better
  • PROGNOSIS (What’s going to happen):
    • Occult dilated cardiomyopathy (before clinical signs occur)
      • with good care, many of these pets will live for 1-3 years before developing clinical signs
    • Clinical dilated cardiomyopathy (after clinical signs are present)
      • In Doberman pinschers, prognosis remains poor
        • many dogs will die either suddenly of a heart attack, or have recurrent, severe pulmonary edema (congestive heart failure fluid in the lungs)
      • In other breeds, with good care, many dogs will live more than 6-12 months
        • With good quality of life
  • FOLLOW UP CARE:
    • Monitoring
      • Monitoring at home consists of monitoring eating and activity, and to note breathing and coughing patterns. Because fluid in the lungs causes increased breathing rates as the first sign of congestive heart failure, noting breathing rates is very important. See our Resting Breathing Rates page
    • In the immediate short term, followup laboratory work and radiographs are often required to adjust medications
    • In the long term, followup every 2-4 months is generally performed
      • The testing performed often is case dependent
        • often depends on the signs you are seeing with your pet

Quick Info

DEFINITION (What it is): Dilated cardiomyopathy is a disease where the heart, for mostly unknown reasons, quits pumping normally and becomes enlarged and flabby.
EPIDEMIOLOGY (Who gets it): Dilated Cardiomyopathy is a disease of large and giant breed dogs
CAUSE: In Doberman pinschers, there are two genes identified. Since other breeds can be commonly affected, there is probably a genetic component in them as well
CLINICAL SIGNS: None (occult dilated cardiomyopathy.Increased breathing rate (> 30-35 breaths per minute). Coughing. Exercise intolerance or weakness. Fainting. Sudden death. Loss of appetite. Weight loss. Distended belly
POSSIBLE DIAGNOSTICS: Echocardiography (heart ultrasound). Radiographs (x-rays). Electrocardiogram. Doppler Blood Pressure. Holter Monitor
THERAPY: Therapy is medical in nature
PROGNOSIS: Occult, many of these pets will live for 1-3 years before developing clinical signs. Clinical, prognosis remains poor
FOLLOW UP CARE: The testing performed often is case dependent