Congestive Heart Failure: CHF in Dogs

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CHF is the condition during which a dog's heart is unable to pump enough blood to all the body's tissues.

What Causes CHF in Dogs?

In dogs, the two most common causes of CHF are:

• Mitral valve insufficiency. This is when the valve between the two chambers of the left side of the heart leaks. It's the most common cause of CHF in dogs, especially small breeds.
• Dilated cardiomyopathy. This is when the heart's muscle isn't strong enough to build enough pressure to pump blood adequately. It is the most common cause of CHF in large breed dogs.

Other conditions, such as arrhythmias (as in the case of boxer cardiomyopathy), narrowing of the major arteries, and high blood pressure can also cause CHF.

What Are the Signs of Canine CHF?

Signs of CHF in dogs are different depending on whether the dog is in left-sided or right-sided heart failure.

• Left-sided heart failure occurs when some of the blood in the heart's lower left chamber (the left ventricle) leaks back up into the upper chamber (the left atrium) when the heart tries to pump it out to the body. It's the most common type of CHF. Fluid begins to seep into the lung tissue, which causes pulmonary edema. Signs of left-sided CHF include:

  • Coughing that is often worse at night
  • Difficulty breathing that is often worse at night
  • Increased respiratory rate
  • Exercise intolerance
  • Weakness
  • Syncope (fainting)

• Right-sided heart failure occurs when the lower right side of the heart (the right ventricle) tries to pump blood to the lungs to oxygenate it, but some leaks back into the upper chamber (the right atrium). The blood backs up into the circulatory system and results in fluid building up in the abdomen (ascites) or legs. Heartworm disease is a significant cause of right-sided CHF in dogs. Signs of right-sided CHF include:

  
  • Swollen abdomen
  • Swelling in the limbs
  • Weakness
  • Lethargy
  • Exercise intolerance
  • Labored breathing
  • Increased respiratory rate

How Do Vets Diagnose CHF in Dogs?

CHF is diagnosed through physical examination and a history of signs related to heart disease, such as coughing, weakness, and syncope. Some dogs will have high kidney values on blood work but normal urine concentrating ability. On chest x-rays, the heart may look enlarged (either the right or left side depending on the type of CHF). Pulmonary edema or abdominal ascites may be visible on x-rays.

An echocardiogram can show many different changes in the heart and blood flow and is most helpful in diagnosing CHF.

What Is the Treatment for Congestive Heart Failure in Dogs?

The treatment for CHF in dogs depends on the type of heart failure and the secondary conditions occurring because of it. Treatments may include:

• Diuretics to remove pulmonary edema or ascites
• Heart medications to help control arrhythmias or aid the heart's pumping mechanisms
• Drugs that dilate blood vessels
• Supplements to help control electrolyte imbalances
• Surgery for some conditions, such as PDA
• Heartworm treatment for heartworm disease
• Other treatments as necessary for various causes of CHF

Monitoring is required to determine how the dog is responding to treatment and whether medications need to be altered. Prognosis depends on the individual condition.

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