Canine Congestive Heart Failure

Congestive Heart Failure (CHF) and Heart Disease

Congestive heart failure occurs when there is a heart abnormality leading to the failure of the heart to pump enough blood to meet the body’s needs. CHF is not a specific disease – it is a condition in which congestion (fluid accumulation), decreased blood flow to the body, and/or abnormally low blood pressure arise as the final consequence of severe heart disease.

Heart disease refers to a variety of conditions that involve narrowed or blocked blood vessels. Heart disease is a common problem in dogs and can be caused by a number of underlying diseases including heart valve degeneration, heart muscle disease and irregular heart rate and rhythm (arrhythmia). Heart disease can be present without ever leading to CHF. However, CHF can only occur in the presence of heart disease because it is a result of severe heart disease.

CAUSES OF CONGESTIVE HEART FAILURE (CHF)

Congestive heart failure (CHF) is a severe heart disease that refers to the heart’s inability to pump adequate blood to the body. There are many causes of CHF in dogs. The two common causes are:

• Valvular degeneration is the most common cause of canine CHF.
• Dilated cardiomyopathy (DCM) is the second most common cause of canine CHF.

Mitral Valve Disease (MVD)

Mitral Valve Disease (MVD) occurs when damaged and thickened valves develop within the heart of dogs. If the valves fail to close completely when the heart contracts, blood moves forward but some leaks backward. Fluid accumulates when the heart fails to pump enough blood to the body and instead the blood is transmitted backward from the heart to the lung or body. Cardiac function and circulation are then hindered.

Dilated Cardiomyopathy (DCM)

With this disease the heart muscle becomes weak and large, preventing it from pumping blood efficiently. This causes decreased cardiac output and tissue perfusion.

COMMON CLINICAL SIGNS OF CHF:

In the early stages, signs are usually subclinical (symptoms are not obvious yet). This phase can last months or years. Valvular disease progresses slowly, but DCM can have a quick onset and progresses rapidly. Both eventually lead to CHF. As either progresses, common clinical signs may include:

• Persistent coughing, when at rest or sleeping, accompanied by difficulty breathing due mainly to the accumulation of fluid in the lungs (pulmonary edema). Irritation can induce a cough since the enlarged heart pushes against the trachea.
• Fatigue – dogs with CHF may tire out more easily and have reduced stamina.
• Lethargy – they do not engage in playing or walking as they once did.
• Persistent loss of appetite, a swollen belly, and pale or bluish gums.
• Generalized weight loss and muscle wasting due to the effects of CHF on other body systems.
• Fainting spells.
• Difficulty sleeping, especially for dogs who sleep on their sides.

DIAGNOSIS OF CHF

When it comes to diagnosing CHF, it’s crucial that detection happens early and quick treatment follows. The problem, however, is that the clinical signs and symptoms can be similar to respiratory disease. Diagnosis involves several tests that may include:

• Clinical History (assess age, breed and history in terms of behavior, breathing, appetite, etc.)
• Physical Examination (examine weight and body condition, pulse abnormalities, etc.)
• Cardiac and Pulmonary Auscultation (to detect a heart murmur caused by blood leakage)
• Chest X-rays (to assess heart size, changes in the lungs, such as presence of fluids, etc.)
• Additional Diagnostic Tests (blood and urine tests, echocardiography, electrocardiograms, etc.)

Once you notice signs of heart disease, you should consult your veterinarian as soon as possible so that diagnostic tools can provide answers. Unfortunately, there is no cure for CHF, but therapeutic intervention can improve symptoms and prolong life.