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Heart Disease in Dogs: Causes, Symptoms, and Treatment

If you're a dog owner, you likely know how much your furry friend loves to run, play, and explore. Dogs are active and enthusiastic creatures who enjoy life to the fullest. However, what if your dog's heart isn't functioning properly? What if your pet develops heart disease?

Heart disease is a common condition that affects many dogs, especially as they age. It can hinder the heart's ability to circulate blood to the rest of the body, leading to severe and potentially fatal complications. In this article, BestForPets will discuss the causes, symptoms, and treatment options for canine heart disease, as well as how to keep your furry companion healthy and happy.

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Deborah R. Fletcher (DVM)


The information provided is current and up-to-date, in line with the latest research conducted in the field of veterinary medicine.

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What Is Heart Disease in Dogs?

Heart disease in canines refers to a variety of conditions that affect the structure or function of the heart. Some dogs are born with congenital heart disease, while others develop heart problems later in life due to a variety of factors (acquired heart disease). Depending on the nature and severity of the condition, heart disease may affect one or both sides of the heart.

Congestive heart failure (CHF) is one of the most common outcomes of canine cardiovascular disease. This results in fluid accumulation in or around the lungs (left-sided CHF) or the abdomen or extremities (right-sided CHF). CHF can cause respiratory difficulties, fatigue, edema, and other symptoms that can reduce the quality and duration of your dog’s life.

What Causes Heart Disease in Dogs?

There are numerous factors that can contribute to cardiac disease in dogs, including:

  • Age: As dogs age, their hearts may deteriorate, making older dogs more susceptible to cardiac conditions than younger dogs.
  • Breed: Some breeds may be more predisposed to certain types of cardiac disease due to genetic factors. Small breed dogs, such as Cavalier King Charles Spaniels, Chihuahuas, and Poodles, may be more susceptible to cardiac valve disease, while large breed dogs, such as Doberman Pinschers, Boxers, and Great Danes, may be more susceptible to myocardial disease.


  • Diet: A diet high in sodium or fat can increase the risk of hypertension, obesity, and cholesterol buildup, all of which can impair cardiac function.
  • Obesity: Being overweight can increase the risk of diabetes, which can impair the blood vessels and nerves that supply the heart.
  • Infection: Bacterial or viral infections can cause inflammation or injury to the heart valves or muscle, resulting in endocarditis or myocarditis.
  • Illness: Other conditions or diseases that affect the organs or systems of the body can also impact the function of the heart. Kidney disease, thyroid disease, anemia, or cancer, for example, can cause alterations in blood volume, blood pressure, or oxygen levels, which can strain the heart.

Some specific types of heart disease in dogs include:

  • Heart valve disease: This occurs when valves that regulate blood flow between the heart’s chambers become leaky or rigid, resulting in a cardiac murmur and decreased efficacy. Myxomatous mitral valve degeneration (MMVD) is the most common form, affecting elderly, small-breed dogs.
  • Myocardial disease: This condition occurs when the heart muscle becomes weak or thick, impairing its capacity to contract and relax. Dilated cardiomyopathy (DCM), which affects large-breed dogs and causes thinning and enlargement of the heart chambers, and hypertrophic cardiomyopathy (HCM), which affects cats more than dogs and causes thickening and stiffening of the heart walls, are the most common types.
  • Heartworm disease: This occurs when the heart and lungs are infected by parasites transmitted by mosquitoes, causing inflammation and injury. Heartworms can obstruct blood flow from the right side of the heart to the lungs, resulting in right-sided congestive heart failure.
  • Arrhythmias: This occurs when the heartbeat is too rapid, too sluggish, or irregular, interfering with the heart’s normal electrical activity. Several factors, including genetics, medications, electrolyte imbalances, and underlying diseases, can cause arrhythmias. Atrial fibrillation (AF), which causes rapid and chaotic contractions of the upper chambers, ventricular tachycardia (VT), which causes rapid and potentially lethal contractions of the lower chambers, and bradycardia (BR), which causes sluggish and weak contractions of either chamber, are some common types.
  • Shunts: This occurs when abnormal blood vessels or cavities divert blood away from the normal circulation, reducing tissue oxygenation. Most canine cardiac shunts, such as patent ductus arteriosus (PDA) and ventricular septal defect (VSD), are congenital (present at birth). PDA is the failure of a vessel connecting the aorta and pulmonary artery to close after delivery, allowing blood to bypass the lungs. A VSD occurs when a fissure in the wall separating the ventricles permits the mixing of blood from the left and right regions of the heart.
  • Stenosis: This occurs when a constriction of a valve or vessel obstructs blood flow, increasing the heart’s pressure and exertion. The majority of stenosis cases in dogs are congenital, including pulmonic and subaortic stenosis. PS occurs when the valve between the right ventricle and pulmonary artery is too restrictive, limiting blood supply to the lungs. SAS occurs when the area beneath the valve between the left ventricle and the aorta is too narrow, thereby restricting blood flow to the body.
  • Pericardial disease: This condition occurs when the sac that surrounds the heart becomes inflamed or filled with fluid or air, impairing its function. The most common type is pericardial effusion, which occurs when fluid (usually blood) accumulates in the space between the pericardium and the heart, preventing the heart from filling adequately and compressing it.

What Are the Symptoms of Heart Disease in Dogs?

Different forms of heart disease can induce various symptoms, but the following are some of the most common:

What Are the Symptoms of Heart Disease in Dogs

  • Persistent coughing, especially when lying down or sleeping: This may indicate fluid accumulation in or around the alveoli as a result of left-sided cardiac failure or heartworm disease.
  • Difficulty breathing or rapid breathing: This may indicate decreased oxygen delivery to the tissues as a result of inadequate blood flow or fluid accumulation in or around the lungs.
  • Reduced exercise tolerance or fatigue: This may indicate decreased blood flow to the muscles as a result of inadequate cardiac output or arrhythmias.
  • Fainting or collapsing episodes: This may indicate a decrease in blood flow to the brain as a result of inadequate cardiac output, arrhythmias, or low blood pressure.
  • Swelling of the abdomen or limbs due to fluid accumulation: Increased pressure in the veins that evacuate blood from these areas may indicate right-sided congestive heart failure (CHF).
  • Loss of appetite or weight loss: This may indicate decreased blood flow to the digestive organs due to inadequate cardiac output or abdominal fluid accumulation.
  • Restlessness or anxiety: This may indicate discomfort or distress caused by difficulty inhaling, pain, or low oxygen levels.

Some dogs may not exhibit symptoms until their condition has progressed, so routine examinations and screenings are essential for early detection and treatment. If you observe any of these symptoms in your dog, you should consult a veterinarian immediately.

What Are the Treatment Options for Heart Disease in Dogs?

Treatment options for heart disease in dogs depend on the type and severity of the condition, as well as the dog’s age and general health. Your veterinarian will conduct a comprehensive physical examination and diagnostic tests, such as blood tests, chest x-rays, an electrocardiogram (ECG), echocardiogram (ultrasound), or angiogram (contrast dye), to determine the most appropriate course of action. Among the potential remedies are:

What Are the Treatment Options for Heart Disease in Dogs

1. Medications:

These are used to increase blood flow, decrease fluid retention, regulate cardiac rhythm, reduce blood pressure, and prevent blood clotting.

Diuretics (to remove excess fluid), angiotensin-converting enzyme inhibitors (ACE inhibitors) (to dilate blood vessels), beta-blockers (to slow heart rate), calcium channel blockers (to relax heart muscle), antiarrhythmics (to correct abnormal rhythms), anticoagulants (to prevent clots), and vasodilators (to widen blood vessels) are a few examples.

2. Surgery:

This is used to repair or replace faulty heart valves, remove tumors or blockages, close shunts, and implant pacemakers or defibrillators.

Surgical procedures can be either invasive (requiring an incision and thoracic cavity opening) or minimally invasive (using tiny instruments inserted through small incisions or catheters inserted into blood vessels).

3. Interventional procedures:

Using catheters or balloons, these are used to dilate constricted vessels or valves or to insert stents or coils to obstruct shunts or aneurysms. These procedures are less invasive than surgery, but they carry greater risks of complications such as hemorrhage, infection, or embolism.

4. Supportive care:

This is utilized for oxygen therapy, fluid therapy, nutritional supplementation, pain relief, and palliative care. Supportive care may enhance your dog’s welfare and quality of life, but it does not treat the underlying cause of heart disease.

How to Prevent and Manage Heart Disease in Dogs

Although some forms of canine heart disease are unavoidable due to genetic factors, there are methods to prevent or reduce the risk of developing heart issues, including:

How to Prevent and Manage Heart Disease in Dogs

1. Feeding a balanced and high-quality diet that is low in salt and fat:

A healthy diet can help maintain a healthy weight and prevent obesity, which can put additional stress on the heart. It can also help prevent or manage other conditions that can affect heart function, such as diabetes, hypertension, and high cholesterol.

Discover the top dog foods for heart disease that can help improve your furry friend’s cardiac health and well-being.

2. Providing regular exercise and mental stimulation:

Exercise can help strengthen the cardiac muscle and improve blood circulation. It can also help prevent obesity, diabetes, and high blood pressure, all of which can impair cardiac function. Mental stimulation can help reduce stress and anxiety, both of which can affect heart function.

3. Keeping up with vaccinations and parasite prevention:

Vaccinations can help protect your dog against infectious diseases that can cause inflammation or cardiac injury. Heartworm disease is a potentially life-threatening condition that affects the heart and lungs and can be prevented through parasite control.

4. Avoiding exposure to tobacco smoke or other toxins:

Tobacco smoke and other pollutants can irritate the respiratory system and reduce tissue oxygenation. They can also increase the risk of cancer, which can impair cardiac function.

If your dog has been diagnosed with heart disease, you should follow your veterinarian’s instructions and monitor any symptom or behavioral changes. Methods for treating cardiac disease in dogs include:

  • Giving medications as prescribed and keeping track of doses and refills: Medication can help improve your dog’s health and extend their lifespan, but it must be administered regularly and correctly. You should also be aware of any potential side effects or drug interactions.
  • Scheduling regular follow-ups and tests to evaluate progress and response to treatment: Your veterinarian will need to evaluate your dog’s heart function and adjust the treatment plan accordingly. You should also promptly report any new or worsening symptoms or concerns to your veterinarian.
  • Providing a comfortable and stress-free environment for your dog: You should provide your dog with a comfortable, distraction-free place to rest and sleep, away from loud noises and other disturbances. You should also avoid extreme temperatures and humidity, which can affect your dog’s ability to breathe. Additionally, you should show your dog affection and avoid leaving them alone for long periods.
  • Seeking emergency care if signs of CHF or other complications occur: CHF is a medical emergency that requires immediate treatment. Symptoms of congestive heart failure include rapid or labored breathing, pale or blue gums, coughing up blood, seizures, or collapsing. If you observe any of these symptoms in your dog, you should immediately take them to the nearest veterinary clinic or hospital.


Heart disease is a severe condition that can negatively impact the quality and length of a dog’s life. It can be caused by factors such as age, breed, genetics, diet, obesity, infection, or illness. It can also lead to congestive heart failure, a potentially fatal complication that occurs when the heart cannot pump enough blood to the body.

Depending on the type and severity of the disease, symptoms of heart disease in dogs may include persistent coughing, difficulty breathing, reduced exercise tolerance, dizziness, swelling, loss of appetite, or restlessness. Some dogs may not exhibit symptoms until their condition has progressed, so routine examinations and screenings are essential for early detection and treatment.

Although heart disease can have a significant impact on a dog’s life, with proper diagnosis and treatment, many dogs can live longer and happier lives. If you have any concerns or questions about your dog’s cardiac health, you should consult your veterinarian immediately.

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Dr. Deborah Fletcher

Deborah R. Fletcher, DVM, is a skilled veterinarian with more than 15 years of experience dealing with companion and exotic animals. She has experience caring for a variety of animals, including household cats and dogs, reptiles, birds of prey, and even primates. Dr. Fletcher is a valuable part of the BestForPets team, where she contributes to their aim of providing pets and their owners with the finest possible treatment and services.

Veterinarian (DVM) Dr. Deborah Fletcher


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