Cardiomyopathy in Dogs and Cats

Posted on June 12, 2015

When a heart functions abnormally, it’s called cardiomyopathy.  It is a disease than can manifest with rapid progression and sudden death in both dogs and cats.  Others do not develop clinical signs.  Some cases are reversible, while others are treated with variable levels of success.

Signs of cardiomyopathy.

1.  Fatigue, fainting and inability to exercise; each may indicate abnormal function

2.  Collection of fluid in the lungs, abdomen and limbs.

3.  Clots, called emboli arising in the heart and traveling to the kidney, brain and legs.

4. Weight loss may occur.

5. Seizures with fainting may occur.

6. Blood vessel blockage

7. Sudden lameness

8. Cold and painful limbs

9.  Irregular heart rythym and rate

10. Abnormal heart sounds

Causes of cardiomyopathy

1.  Genetics

2. Toxins, such as drugs and compounds

3.  Infections

4.  Diet insufficiencies


Other causes Three forms of cardiomyopathy.  Dialated is usually the form shown in dogs, while hypertrophic and unclassified forms are identified most often in cats.

1. Dialated cardiomyopathy is a weak and flaccid heart muscle with a reduction in function during contraction called systole and a decrease in forward flow. The upper heart chamber, left atrial is enlarged with backup blood and fluid in the lungs called pulmonary edema.

2.  Hypertrophic cardiomyopathy is a thickening of the lower heart muscle chambers called the ventricles, resulting in inappropriate function and obstruction of blood flow from the heart into circulation.  There is enlargement of the atria or upper heart chamber called diastolic dysfunction.  The heart fails to relax fully, fill and empty resulting in pressures into the lung resulting in respiratory distress, coughing and blood clots.

3.  Unclassified or restrictive cardiomyopathy is identified by a dysfunctional ventricular muscle and inability of the heart to fill and pump adequately.  The upper chambers are enlarged diminishing the ability to pump.


1. Clinical signs usually develop suddenly without prior illness.

2.  Diagnosis is usually found apon physical examination.

3. Stethoscope is used to listen for abnormal heart sounds.

4. Chest x-rays show an enlarged heart.

5.  Electrocardiogram can help diagnose an irregular heart beat and enlargement.

6. Ultrasound of the heart can confirm cardiomyopathy

7.  Blood evaluation to determine complicating organ problems Treatment varies depending on the type of cardiomyopathy.

Dialated Cardiomyopathy Treatment

1. A medication called digitalis improves the strength.

2. A diuretics to remove excess fluid accumulation

3. Angiotensin-converting enzyme inhibitors are used to counteract abnormal hormone levels contributing to heart failure.

4. A low salt diet to reduce water retention

5. Taurine and carnitine nutrients may counteract specific nutrients.

Hypertrophic and Unclassified Cardiomyopathies Treatment

1. Medication such as Beta-adrenergic blocking agents or calcium-channel blocking agents are used to allow the ventricular muscle to relax, improving heart filling and blood flow to the body.

2. Diuretics for the removal of excess fluids from the body.

3. Manual removal of fluids from the chest space to improve comfort.

4. Low salt diet for water retention

5. Aspirin to lower the likelihood of blood clots in the heart.

6. Antiarrhythmic agents to control irregular heart rate and rhythm.

7.  Taurine and/or carnitine as nutritional supplements Prognosis Survival with cardiomyopathy varies from poor to good.

Damage to a heart muscle has already occurred when diagnosed resulting in congestive heart failure and treated over a variable period of time, three months to a year. Pets can enjoy a period of health, the prognosis exists that the heart failure will recur and less responsive to medical intervention.  Surgery is not an option.