Lanebern Saint Bernards
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.
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
- 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. Such treatment can & must only be prescribed by your vet!
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)
A number of other diseases can be easily confused with dilated cardiomyopathy unless an appropriate diagnostic evaluation is completed.
A complete medical history should be obtained and your veterinarian should complete a thorough physical examination. Medical tests are needed to establish the diagnosis, exclude other diseases, and determine the impact of this disorder on your pet. The following diagnostic tests are often recommended:
- A thorough physical examination. Special attention is paid to auscultation (stethoscope examination) of the heart. Heart murmurs, abnormal heart sounds, and irregular heart rhythms may indicate a problem with the heart.
- Thoracic radiographs. X-rays of the chest identify heart enlargement and fluid accumulation in the chest.
- An electrocardiogram (EKG). While this test is often abnormal in cases of serious heart disease, it can be normal in many other pets with heart disease.
- An echocardiogram. An ultrasound examination of the heart is required for establishing the diagnosis of DCM.
The principles of therapy depend on the presentation or current condition of the pet. If symptoms are severe, hospital therapy is necessary. Precise treatments depend on the problems caused but may include: treatment of congestive heart failure, control of an arrhythmia or abnormal heart rhythms, management of kidney failure, treatment of low blood pressure or shock caused by severe heart failure, or treatment of complications of thrombosis (blood clots).
- Hospital treatment of severe congestive heart failure includes oxygen, the diuretic furosemide (Lasix®), and often nitroglycerin or nitroprusside. If blood pressure is low or heart function very bad, the drug dobutamine, which is a stimulant of heart contraction, is often recommended for 24 to 72 hours.
- Optimal treatment for your pet with dilated cardiomyopathy requires a combination of home care and professional veterinary care. Follow-up can be critical. Administer prescribed medication and alert your veterinarian if you are experiencing problems treating your pet. Optimal follow-up care often involves the following:
- Administering prescribed medications. Remember erratic administration of medication is a common reason for treatment failure.
- Observe your pet's general activity level, appetite, and interest. These are quality-of-life issues of importance to you and your pet.
- Watch your pet for labored or rapid breathing or for coughing. If possible, learn to take a breathing rate when your pet is resting. Ask your veterinarian about this.
- Follow-up chest X-rays may be required to monitor the response to therapy.