We all want our dogs to live for as long as possible, so it can be scary to think of them developing an illness like heart disease, which affects their daily functioning and life expectancy. Heart disease is a condition that dogs are either born with (congenital) or develop (acquired) through a combination of factors like age, diet, illness, or infection.
In some dogs, heart disease can lead to a condition known as congestive heart failure. This occurs when the valves, which regulate blood flow to and from the heart, stop working properly. Since congestive heart failure can be mistaken for other illnesses that accompany the aging process, it’s important for early detection and treatment to recognize when a dog is showing signs of this condition.
What Is Congestive Heart Failure in Dogs?
According to the Merck Veterinary Manual, congestive heart failure (CHF) isn’t a specific disease. Instead, it’s a condition that occurs when the heart is unable to pump an adequate amount of blood throughout the body, says Dr. Jerry Klein, DVM, Chief Veterinary Officer for the American Kennel Club. CHF can progress slowly, affecting one or both sides of the heart.
Before getting into the symptoms of heart failure, it helps to understand how a healthy heart is supposed to function. Firstly, the canine heart has four valves (flaps of skin that keep blood flowing in one direction). Valves are located between the four chambers of the heart: the left and right atria and the left and right ventricles. In a healthy heart, the right ventricle pushes blood through the lungs so it can pick up oxygen. The left ventricle pushes the oxygenated blood into circulation so it can travel to wherever it’s needed in the body.
As the heart is pumping blood, the valves open and close, which is the sound you hear when you listen for the heartbeat. “When a valve doesn’t close properly or leaks, the blood doesn’t flow into the following chamber and instead can ‘leak’ back into the previous chamber,” Dr. Klein says. Accordingly, a heart murmur can be an early sign that a valve is leaking. Instead of the “lubb-dupp” sound of a normal heartbeat, a heart murmur can have a swishing or whooshing sound. “Though a heart murmur may be detected early in life, heart failure may not develop until much later in life,” Dr. Klein adds.
What Are the Symptoms of Congestive Heart Failure?
Knowing what symptoms to look for depends on the source of the problem. As Dr. Klein explains, “there are two basic forms of CHF: left-sided failure and right-sided failure.” Since left-sided CHF is more common, there’s greater awareness of the accompanying symptoms, including:
- Persistent, usually moist cough, even when the dog is resting or sleeping
- Increased and often shallow respiratory rate
- Labored breathing, even when the dog is not coughing
- Tiring easily
- Pale or cyanotic (blueish) gums and mucous membranes, usually accompanied by a heart murmur
The symptoms most often associated with right-sided CHF are:
- Coughing
- Tiring from exercise
- Swollen abdomen (ascites)
- Possible swelling of the extremities (peripheral edema), also associated with a heart murmur
Stages of Congestive Heart Failure
In addition to there being different forms of CHF, there are also different stages of this condition. Here is what a veterinarian will look for at each stage.
Stage A
The dog is at a high risk of developing heart disease based on age and breed. However, they aren’t showing any overt clinical signs, such as weakness or a persistent cough. This stage can last for years.
Stage B
The dog has a heart murmur that can be heard with a stethoscope. They may not be exhibiting clinical signs of heart failure.
Stage B2
The dog has a detectable heart murmur but isn’t showing clinical signs. There are structural changes to the dog’s heart that can be seen with an X-ray or electrocardiogram.
Stage C
The dog is showing signs of heart disease and is responsive to cardiac medications.
Stage D
This stage is referred to as “end-stage,” because the dog is exhibiting severe symptoms and is no longer responding to cardiac medications or treatments.
What Causes Congestive Heart Failure in Dogs?
Valvular Disease
Among the many causes of congestive heart failure is valvular disease, which accounts for approximately 80 percent of cases in dogs, Dr. Klein says. The most common type of valvular disease in dogs, mitral valve disease, occurs when the mitral valve leaks. The mitral valve is located between the left atrium and the left ventricle. When the heart contracts, a properly working mitral valve helps ensure that the left ventricle is pushing blood into circulation.
Left-sided heart failure occurs when the mitral valve leaks blood back into the left atrium, which then accumulates in the lungs. “Fluid then seeps back into the lung tissue, resulting in pulmonary edema which causes coughing and difficulty breathing,” Dr. Klein explains.
Right-sided heart failure occurs when blood leaks through “the tricuspid valve (the valve between the right atrium and right ventricle) back into the right atrium,” Dr. Klein explains. “The blood then backs up into systemic circulation and causes congestion.” The resulting accumulation of fluid in the abdomen is called ascites.
Dilated Cardiomyopathy
Another common cause of congestive heart failure is dilated cardiomyopathy (DCM). “This occurs when the heart muscle itself is diseased and loses its innate ability to contract, making the heart an inefficient pump,” Dr. Klein says. As a result, the flow of blood will slow, leading to reduced blood pressure.
Biventricular failure occurs when both ventricles, left and right, are not functioning properly. Merck Veterinary Manual states that dilated cardiomyopathy or poisoning can result in biventricular failure. With this type of CHF, you might see symptoms of both left and right-sided heart failure. However, it’s common for one set of symptoms to be more apparent than the other.
Dr. Klein notes there have been reports of heart issues (DCM) associated with certain diets, notably grain-free diets or diets containing peas or legumes as one of the primary sources of energy in the food. While conclusions are pending, he recommends discussing this concern with your veterinarian.
Other Causes of CHF
Besides valvular disease and dilated cardiomyopathy, other causes of CHF are:
- Defects in the walls of the heart
- Congenital cardiac defects
- Arrhythmias
- Narrowing of major blood vessels
- Heartworms
- Accumulation of fluid in the pericardium (sack around the heart)
- Infection (endocarditis)
- Tumors or cancer
Which Dogs Are Most at Risk?
Congestive heart failure tends to happen more often in middle-aged and older dogs, but it can affect dogs of any age, breed, or sex, Dr. Klein explains. Certain breeds are predisposed to dilated cardiomyopathy, including the Doberman Pinscher, Great Dane, Boxer, and Cocker Spaniel, suggesting that there might be a genetic component to this disease.
Small dog breeds may develop CHF due to mitral valve issues, which are the most common cause of this condition. Some large and giant dog breeds are prone to developing CHF because of issues like dilated heart muscles or cardiomyopathy.
What Treatment Can You Provide for a Dog with Congestive Heart Failure?
A general practice veterinarian can provide a referral to a board-certified veterinary cardiologist who specializes in treating patients with heart issues. “With their continued monitoring and guidance, they are the ones who can give the best advice on the management and prognosis of the patient such as nutrition, medication, and activity,” Dr. Klein says.
For instance, they can recommend an appropriate amount of exercise or a low-sodium diet to reduce pressure on the heart. In addition, a veterinary cardiologist may prescribe medications to help remove fluids and slow the progression of CHF.
How Long Can Dogs Live with Congestive Heart Failure?
In general, dogs that are diagnosed with congestive heart failure can live anywhere from 6 months to 1 1/2 to 2 years. Other factors that affect how long a dog can live with CHF include:
- The age of the dog
- The severity of their condition
- Any medications the dog is taking
- How responsive the dog is to treatment
- Any underlying medical conditions, such as kidney disease or pneumonia
“There is no cure for heart failure in dogs,” Dr. Klein says. “Early detection and proper management are crucial to improving a dog’s prognosis and quality of life.”
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