Congestive Heart Failure in Dogs

Heart disease can cause a variety of health problems in dogs, but some complications are more severe than others. Congestive heart failure (CHF) is a severe heart condition that can affect dogs, cats, and humans, occurring in some cases of advanced heart disease. Like other types of heart failure, CHF can cause symptoms like difficulty breathing, coughing, panting, loss of appetite, distended abdomen, and pale or blue gums. This is due to the heart pumping blood improperly to the body, which results in blood congestion and swelling within the organs; typically affecting the lungs. About 80 percent of CHF cases in dogs are caused by mitral valve insufficiency (MVI), which is most common in small breeds. Prompt treatment is necessary to relieve discomfort, ease breathing, and prevent death.

What Is Congestive Heart Failure?

Congestive heart failure (CHF) occurs in some advanced stages of heart disease when the heart is unable to properly pump blood, leading to the buildup of blood in other parts of the body including major organs like the lungs. CHF is not a disease itself, but a syndrome characterized by fluid accumulation in cases of heart disease. Specific signs vary depending on which side of the heart is diseased, although congestive heart failure may affect both sides of the heart if there are problems in both the left and right ventricles. To understand the differences in CHF cases, it's helpful to first learn how the heart works.

The heart is comprised of four chambers: the right atrium, the right ventricle, the left atrium, and the left ventricle. There are valves between these chambers that regulate blood flow through the heart. In a normally functioning heart, the veins of the body deliver deoxygenated blood through the right atrium into the right ventricle. The blood flows through the pulmonary artery and becomes oxygen-rich. The blood is then pumped into the left ventricle and goes through the left atrium out to the body via the arteries. When a disease is present in one or more areas of the heart, the blood cannot flow properly. Fluid can build up in the heart and surrounding areas, leading to congestive heart failure.

Types of Congestive Heart Failure in Dogs

• Left-sided congestive heart failure: This causes pressure to back up in the vessels that pump blood into the left ventricle of the heart. Blood leaks through the mitral valve, which causes excess fluid to become congested in the lungs. Fluid accumulates in the lungs (called a pulmonary edema) and leads to coughing, exercise intolerance, difficulty breathing, and a high respiratory rate.
• Right-sided congestive heart failure: This causes pressure to build up in the vessels where blood flows into the right atrium from the veins in the body. Rather than leaking through the mitral valve, blood leaks where it is pumped into the heart and becomes congested within the body. This pressure can lead to fluid buildup in the chest cavity, the abdomen (called ascites), the liver, and even the limbs (called peripheral edema). These dogs can also experience difficulty breathing due to pressure around the lungs.
  

Symptoms of Congestive Heart Failure in Dogs

While it's possible for dogs with either left-sided or right-sided congestive heart failure to experience difficulty breathing, right-sided cases can also involve symptoms like distended abdomen and swollen limbs. Owners of dogs with heart disease or heart murmurs should be on the lookout for the following signs of CHF:

Difficulty breathing is often accompanied by panting and a persistent cough in dogs with CHF. Exercise intolerance, loss of appetite, and pale or blue gums are also common symptoms.

Dogs with left-sided congestive heart failure may even collapse due to obstructed blood flow, as this causes low blood pressure, slowed heart rate, and decreased oxygen supply to the brain. Conditions like dilated cardiomyopathy, hypertrophic cardiomyopathy, mitral valve disease, and several congenital defects affect the left side of the heart and can lead to left-sided CHF.

In cases of right-sided congestive heart failure, dogs often experience a distended abdomen in which the abdominal area appears swollen or bloated. The pressure in the abdomen can affect breathing, digestion, and organ function. Limb swelling (peripheral edema) may also be seen from the congestion of blood in the veins. Because right-sided CHF can also cause fluid buildup around the lungs, dogs with this condition can also experience breathing issues.

Causes of Congestive Heart Failure

Congestive heart failure is caused by underlying heart disease, but there are several different conditions that may lead to this syndrome:

• Mitral Valve Insufficiency (MVI): Mitral valve insufficiency is believed to cause about 80 percent of congestive heart failure cases. MVI occurs when there is a leak in the valve that connects the left atrium and left ventricle. When left untreated, this condition can progress to affect both sides of the heart.
• Cardiomyopathy: Cardiomyopathy occurs when the dog's heart muscles degenerate, which can lead to dilated cardiomyopathy in which the heart expands due to blood pressure.
• Narrow blood vessels: Congestive heart failure can be associated with narrow blood vessels and increased blood pressure.
• Abnormal heartbeat: Also known as arrhythmia, an abnormal heartbeat can cause damage to the muscle and blood vessels if untreated, leading to congestive heart failure.

Diagnosing Congestive Heart Failure in Dogs

Heart disease may be discovered after a routine examination reveals a heart murmur. Although most dogs in congestive heart failure will show some signs of illness, early disease may not be apparent until the veterinarian listens to the heart.

If your dog has already been diagnosed with some form of heart disease, then it is extremely important to see your primary vet or veterinary cardiologist regularly to monitor the progression of the heart disease. Signs of CHF may be detected before outwards signs are present.

Diagnostic tests used to detect and monitor heart disease include the electrocardiogram (ECG or EKG), echocardiogram (ultrasound of the heart), thoracic radiographs (chest X-rays), and blood and urine tests. Your vet will need to periodically repeat these tests to assess the severity of your dog's heart disease.

Treatment

Treatment of congestive heart failure is aimed at managing the underlying heart disease and reducing fluid accumulation. Several different medications are typically used to treat heart disease and may need to be adjusted when CHF develops. Surgery may be recommended if there is a structural abnormality in the heart that can be repaired. A low-sodium diet can also be helpful.

Most cases of left-sided CHF are treated with diuretics. Other heart medications may be used as well. In right-sided CHF, excess fluid may be manually removed, or "tapped," from the abdomen and/or chest cavity. Chest and abdominal taps can provide temporary relief, but the underlying heart disease will cause the fluid to reaccumulate. These dogs often need regular taps of fluid to maintain a good quality of life.

The best thing you can do for your dog with congestive heart failure is to comply with veterinary recommendations and stay in communication with all veterinarians who treat your dog. Give all medications as directed on a regular schedule, and do not make adjustments without your vet's instruction. Feed a diet according to your vet's direction; avoid salty treats, as they can make your dog's condition worse. Monitor symptoms at home and report any changes to your vet immediately.

Prognosis for Dogs With Congestive Heart Failure

The life expectancy of dogs with congestive heart failure depends on the underlying heart disease. CHF cannot be cured unless the primary heart disease can be cured. If corrective surgery can be done to repair structural abnormalities causing the heart disease, then the dog may be able to go on to live a normal life.

Unfortunately, many types of heart disease can only be managed for a period of time (months or years) before they become severe enough to stop responding to treatment. Dogs are in end-stage congestive heart failure when they no longer respond to available treatment options. Often, veterinarians recommend humane euthanasia in this stage before the dog's quality of life becomes excessively poor.

How to Prevent Congestive Heart Failure

While congestive heart failure cannot always be prevented in dogs with heart disease, maintaining proper veterinary care is an important step for owners to help keep dogs healthy. Many treatment options are available for various types of heart disease that can prolong your dog's life or keep CHF from developing. If your dog does not have heart disease, take preventative measures by providing a nutritious diet and plenty of opportunities for exercise. Always consult your veterinarian to determine healthy meal plans, ideal activity levels, and any regular testing that should be performed based on your dog's medical history.