Congestive Heart Failure In Dogs

  1. Introduction
  2. What is congestive heart failure in dogs and what causes it?
  3. Symptoms
  4. Diagnosis
  5. Treatment
  6. Prognosis
  7. Prevention
  8. Sound of normal heart beat and one with a murmur
  9. Video
  10. Emergency


Yep, I have made the break. I’m talking about dogs. But it doesn’t seem such a big change to me. After all there are many families that have both cats and dogs. And many people like both

congestive heart failure in dogs a dog with heartworm

cats and dogs. There is a large overlap. I have written about HCM (Hypertrophic Cardiomyopathy) in cats (link 1link 2). This is a nasty heart disease that results in the thickening of the heart wall. There is a sort of crisis in the Bengal cat fraternity about it as it affects the beautifully athletic Bengal cat to a concerning level. Damn, I’m back to cats again…. Actually, congestive heart failure affects cats and dogs so this post is about cats too! It is the most common heart problem in our canine friends1, especially in smaller breeds2. The disease normally affects older, overweight dogs.

What is congestive heart failure in dogs and what causes it?

The title gives us the clue as to what congestive heart failure in dogs is. The dog’s heart fails to adequately supply the

diagram of a heart

organs of the body with sufficient supplies of blood to meet needs. The health of the major organs such as the kidneys, lungs, liver and other organs are impaired as a consequence3. The reason why the heart fails to perform adequately is due to these possible reasons4:

  1. Myocardial Failure: means a defect in myocardial contraction or an abnormality of myocardial function5. Myocardial means: muscles of the heart6. The ventricles don’t contract strongly enough resulting in the blood being pushed from the heart with insufficient force. The underlying cause of the weakened muscle contraction could be (a) drugs. It is said that all drugs should be treated as poisons7, (b) not enough blood (carrying oxygen) getting to the heart, (c) the chambers of the heart are too large, (d) an infected or inflamed heart and/or (e) persistent abnormal rhythms of the heart.
  2. Hereditary weakness8.
  3. Heartworms9. Can cause high blood pressure causing heart to work harder10.
  4. ‘Volume overload’ – too much fluid in the heart. Heart valve defects such as: leaky valves and/or valve degeneration,
    • inflammation of heart valves,
    • chronic anemia. Anemia means less than the normal number of red blood cells or less than the normal quantity of hemoglobin in the blood11.
    • or toxins.
  5. High blood pressure causing the heart to become enlarged. High blood pressure can be caused by narrowing of blood vessels, heartworm disease, which I mention above.
  6. The ventricals. These are the bottom chambers of the heart. They are unable to fill properly resulting in a lower output of blood from the heart to the body.


  1. Sometimes a chronic cough develops12. A violent cough at night and early morning indicates left sided heart failure (LSHF, which means the left side of the heart13. When coughing the dog is trying to get rid of the fluid in the lungs14.
  2. Difficulty in breathing due to exercise (LSHF).
  3. Fainting (LSHF)15.
  4. Agitated and distressed16.
  5. Reduced ability to excercise17.
  6. Enlarged liver or spleen (right sided heart failure – RSHF).
  7. Difficulty breathing due to fluid in the abdomen, the sac surrounding the heart and the lungs (RSHF).
  8. Blue tongue and gums when active.
  9. Potbellied appearance18.
  10. Lethargy19.

Note: One veterinary website says that congestive heart failure in dogs is “a syndrome in which the right side of the heart cannot provide adequate blood flow..”20 This contradicts the above.


Based on symptoms above plus:

  • Thoracic radiographs – producing an image on a radiosensitive surface by radiation other than visible light.
  • Electrocardiogram (ECG) – A graphical recording of the cardiac cycle produced by an electrocardiograph21
  • Echocardiogram – a test of the action of the heart using ultrasound waves to produce a visual display.
  • Thoracocentesis – Thoracentesis (also known as thoracocentesis or pleural tap) is an invasive procedure to remove fluid or air from the pleural space for diagnostic or therapeutic purposes.
  • Abdominocentesis – centesis means puncturing a body cavity or organ with a hollow needle to draw out fluid etc.. In this case the fluid is removed from the belly for diagnosis.


The above video shows a mobile (at an American cat show) tester using Ultrasound on a Persian cat for HCM (referred to above). Ultrasound also tests for kidney disease.


Treatment for congestive heart failure in dogs is about controlling symptoms not cure. Weight control is important as excess weight means the heart has to work harder. Fluid is reduced through drug therapy. Drug therapy to reduce heart rate. Drugs to eliminate parasites. Diuretics to remove excess fluids. Nutrition control to include supplements such as Chelated zinc, B-complex tablet with niacin, L-carnitine and taurine, mineral supplement with chromium and selenium.


There is no cure for congestive heart failure in dogs.


  1. Keep an eye on chronic (long term) infections (e.g. dental disease)
  2. Routine veterinary examinations to diagnose early signs and start treatment in the early stages26.
  3. Lifestyle improvements such as plenty of activity, low sodium diet, clean water as opposed to chlorinated water, high protein food, good dental care to avoid dental disease27.

Sound of normal heart beat and one with a murmur



You can apparently drain fluid from a dog’s lungs by holding him or her upside down (small dogs hold legs, large dog hold hips) for tens seconds!29

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Congestive heart failure in dogs – notes

The two images on this page are presumed to be in the public domain. If I am wrong please tell me.







7 Cat Owner’s Veterinary Handbook by Drs Carlson and Giffin























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