Heart disease in dogs: what every owner should know

June 14, 2024 - 6 min read

The information in this article has been reviewed by Dr. Rebecca MacMillan on June 14, 2024 . Although it may provide helpful guidance, it should not be substituted for professional veterinary advice.

Illustration of a dog, with a speech bubble containing a heart and an electrocardiogram (ECG) line.

Heart disease in dogs can be a daunting diagnosis, but with the right knowledge and care, you can significantly improve your dog's quality of life and potentially extend their lifespan.

Early detection and proper management, with your vet's help, can make your dog's prognosis a lot more promising. So let's get to it!

We'll walk you through the causes, signs, diagnosis, treatment, and management of heart disease in dogs so you can provide the best care possible.

What is heart disease in dogs?

Heart disease in dogs isn't a single condition. It's a broad term that includes various conditions affecting the heart's function, both congenital (present at birth) and acquired (developed over time).

What causes heart disease in dogs?

Heart disease in dogs can stem from various factors, including genetics, age, lifestyle, infections, other medical conditions, and exposure to toxins or specific medications.

Let’s break down a few of them.

Genetics: Are some breeds more at risk?

Doberman pinscher sits on ground in front of beige background

Genetic factors can influence the development of both congenital and acquired heart diseases, which is why it's so important to get your dog from a reputable breeder when possible. There is still no guarantee that your dog won’t develop a heart condition, but it may lessen the chances.

Here are the top 10 commonly affected purebreds:

  1. Cavalier King Charles Spaniels

  2. Doberman Pinschers

  3. Boxers

  4. Great Danes

  5. Poodles

  6. Cocker Spaniels

  7. Pomeranians

  8. English Bulldogs

  9. Golden Retrievers

  10. Newfoundlands

If you adopted one of these purebreds from a shelter or a different source, don't panic! Just know they might be at risk of developing a heart disease. It doesn't mean they will.

Staying up-to-date on preventative care and considering pet insurance before a heart condition (or other unexpected accident or illness) arises is a good idea.

A close-up of a concerned yellow Labrador Retriever with a gentle expression, receiving an examination by a veterinarian whose hands are shown holding a clipboard, in a clinical setting.

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A close-up of a concerned yellow Labrador Retriever with a gentle expression, receiving an examination by a veterinarian whose hands are shown holding a clipboard, in a clinical setting.


As dogs age, their risk of developing heart disease increases. Older dogs are more likely to suffer from conditions like mitral valve disease and dilated cardiomyopathy.

Lifestyle and diet

A dog's lifestyle can significantly impact their heart health. Obesity, lack of physical activity, a poor diet, and a lack of proper preventative care (including heartworm meds in regions affected by the parasite) can contribute to the development of heart disease.

Golden lab stares at a bowl of dry dog kibble being held by a human arm


Certain infections can lead to heart disease in dogs. Bacterial endocarditis, an infection of the heart valves, can cause significant heart problems if not treated promptly.

In some regions, heartworm disease can be another serious condition that can lead to heart failure if not treated. By the time your dog has symptoms, it may be too late to effectively treat them, which is why preventative heartworm medications are so important.

Finally, canine parvovirus is another infectious disease that can cause serious heart problems in affected animals. 

How do dogs get Parvo

Other medical conditions

Medical conditions like hypothyroidism, diabetes, and high blood pressure can contribute to additional strain on the heart in dogs with underlying cardiac issues.

Toxins and specific medications

Certain chemotherapy drugs and some human medications can wreak havoc on a dog's cardiovascular system.

If your dog needs to take medication or receive a treatment (like chemo) that comes with an elevated risk of heart disease, your vet can advise you on the best course of action.

The benefits to your dog's quality of life now may outweigh any potential risks.

Types of heart diseases in dogs

Again, heart disease in dogs can be broadly classified into two categories: congenital heart defects and acquired heart diseases.

Here's a handy chart with some types of heart diseases, breeds vulnerable to developing them, treatment options, and more.

Type of heart disease What it does Breeds predisposed Symptoms Treatment options Potential treatment costs
Patent ductus arteriosus (PDA) A blood vessel called the "ductus arteriosus" fails to close after birth Poodles, German Shepherds, Pomeranians Exercise intolerance, stunted growth, heart murmur Surgery, medication $2,000 - $5,000
Ventricular septal defect (VSD) A hole in the wall separating the lower heart chambers English Bulldogs, Springer Spaniels Fatigue, poor growth, heart murmur Surgery, medication $2,000 - $6,000
Aortic Stenosis Narrowing of the aortic valve, obstructing blood flow from the heart Boxers, Golden Retrievers, Newfoundlands Exercise intolerance, fainting, heart murmur Surgery, medication $1,500 - $4,000
Pulmonic Stenosis Narrowing of the pulmonary valve, obstructing blood flow to the lungs Jack Russell Terriers, Bulldogs, Samoyeds Exercise intolerance, fainting, heart murmur Surgery, balloon valvuloplasty $1,500 - $5,000
Dilated cardiomyopathy (DCM) The heart becomes enlarged and cannot pump blood effectively Doberman Pinschers, Boxers, Great Danes Fatigue, weakness, coughing Medication, diet changes, pacemaker $500 - $2,000 annually
Mitral valve disease (MVD) The mitral valve deteriorates, leading to heart failure Cavalier King Charles Spaniels, Dachshunds Coughing, difficulty breathing, exercise intolerance Medication, surgery, diet changes $500 - $3,000 annually
Hypertrophic Cardiomyopathy (HCM) Thickening of the heart muscle, impeding blood flow Not common in dogs but prevalent in cats Difficulty breathing, fatigue, fainting Medication, diet changes, pacemaker $500 - $2,500 annually
Heartworm disease Parasitic worms living in the heart and blood vessels N/A (caused by mosquito bites, not breed-specific) Coughing Heartworm prevention, medication, surgery $1,000 - $6,000
Arrhythmias (e.g. Atrial Fibrillation) Abnormal heart rhythms affecting blood flow Boxers, German Shepherds, Labradors Irregular heartbeat, fainting, weakness Medication, pacemaker $500 - $3,000
Endocarditis Infection of the inner lining of the heart chambers and valves German Shepherds, Golden Retrievers, Rottweilers Fever, weight loss, heart murmur Antibiotics, surgery $1,000 - $4,000
Pericardial Effusion Accumulation of fluid in the sac surrounding the heart Golden Retrievers, Great Danes, St. Bernards Difficulty breathing, fatigue, swelling Pericardiocentesis, surgery $1,000 - $5,000

Congenital heart defects

Congenital heart defects are structural abnormalities present at birth.

These defects can range from mild to severe and often require early diagnosis and intervention. Common congenital defects include:

  • Patent ductus arteriosus (PDA): A condition where a blood vessel called the ductus arteriosus fails to close after birth.

  • Ventricular septal defect (VSD): A hole in the wall separating the heart's lower chambers.

  • Aortic stenosis: A narrowing of the aortic valve, which can obstruct blood flow from the heart to the rest of the body.

  • Pulmonic stenosis: A narrowing of the pulmonary valve which can obstruct blood flow from the heart to the lungs.

A small, fluffy dog is being examined by a veterinarian wearing a white coat and blue gloves. The vet is using a stethoscope to listen to the dog's chest. A clipboard with a pen is on the examination table in the foreground.

Acquired heart diseases

Acquired heart diseases develop over time and are often related to aging or other health conditions.

Common types include:

  • Dilated cardiomyopathy (DCM): A condition where the heart becomes enlarged and cannot pump blood effectively.

  • Mitral valve disease (MVD): A condition where the mitral valve inside the heart deteriorates, leading to heart failure.

illustration of a healthy heart and damanged heart with mitral valve disease

  • Hypertrophic cardiomyopathy (HCM): A condition characterized by the thickening of the heart muscle, which can impede the heart's ability to pump blood efficiently. This is more common in cats than in dogs, but it still does impact some dogs.

  • Heartworm disease: Caused by parasitic worms living in the heart and blood vessels, typically leading to heart failure.

  • Arrhythmias: Abnormal heart rhythms that can affect the heart's ability to pump blood effectively. These can include atrial fibrillation and ventricular tachycardia.

  • Endocarditis: An infection of the inner lining of the heart chambers and valves, usually caused by bacteria.

  • Pericardial effusion: An accumulation of fluid in the sac surrounding the heart, which can compress the heart and impair its function.

What are the signs of heart disease in a dog?

A black Cockapoo lying down against a light beige background, looking up with a relaxed expression.

Many dogs with heart disease will be asymptomatic in the early stages.

A problem may only be noticed after a routine examination with your vet, e.g., a vaccination or other health check appointment. Abnormalities like changes in heart rate and rhythm or a murmur can be detected by your vet listening carefully with a stethoscope.

While you might not be able to fully cure your dog of heart disease, recognizing the signs of heart failure might make a significant difference in your dog's health and quality of life.

Here are some key general signs to watch for:

  • Coughing (especially at night)

  • Difficulty breathing 

  • Reduced exercise tolerance 

  • Increased restlessness 

  • Anxiety

  • Decreased appetite

  • Fainting spells

  • Fluid buildup in the abdomen or limbs

A close-up of a Cavalier King Charles Spaniel with a black, brown, and white coat, long wavy ears, and dark expressive eyes, sitting against a light beige background and looking directly at the camera.

Diagnosing heart disease in dogs

An accurate diagnosis is super important for effectively treating and managing heart disease in dogs. Here’s how your vet might pinpoint what your dog's dealing with:

Veterinary examination

A thorough veterinary examination is the first step in diagnosing heart disease.

During the exam, your vet will look for physical signs such as coughing, fatigue, and swelling in your dog's abdomen or limbs.

They will use a stethoscope to listen for abnormal heart sounds, such as murmurs or irregular rhythms.

A nervous Jack Russell is calmed by a female veterinarian in an animal hospital prior to a surgical procedure.

They'll also assess your dog's breathing rate and effort to gather additional clues about heart function.

Here are some questions your vet might ask you during the visit:

  • Symptoms: When did they start? How severe are they? Do they occur after exercise or at rest?

  • Medical History: Any previous conditions? Family history of heart disease?

  • Lifestyle: Any recent changes in diet or exercise routine?

  • Medications: Current medications or supplements?

  • General Health: Changes in weight, appetite, or energy levels?

It's helpful to come prepared with some general knowledge written down, so you don't have to think too hard while wrangling an anxious pup in the office.

A doberman sits on a metal table at the vets office

Diagnostic tests

Once your vet has assessed your pet, they'll likely need to run some tests to confirm a diagnosis (as well as the severity of the disease). Here are a few tests that might come up:

  • X-rays: Reveal the size and shape of the heart and the presence of fluid in the lungs or abdomen. They help identify signs of congestive heart failure and heart enlargement.

  • Echocardiogram: An ultrasound of the heart providing detailed images of its structure and function. It helps diagnose conditions like dilated cardiomyopathy (DCM), mitral valve disease (MVD), and congenital defects.

  • Electrocardiogram (ECG): Measures the electrical activity of the heart and can detect arrhythmias (irregular heartbeats).

  • Blood tests: Check for underlying conditions contributing to heart disease, such as hypothyroidism or infections. They can also measure cardiac biomarkers which are indicators of heart muscle damage.

  • Holter monitor: A portable ECG device worn by the dog for 24-48 hours to monitor heart rhythms over an extended period, useful for diagnosing intermittent arrhythmias.

  • Blood pressure measurement: High blood pressure can both contribute to and result from heart disease, so measuring blood pressure helps in managing the condition.

A happy English Cocker Spaniel with a golden coat panting lightly and looking to the side against a plain light background.

Heart disease stages

Heart disease in dogs is often classified into stages, which helps your vet and their team determine treatment strategies.

Heart disease stage Meaning
Stage A Dogs at high risk of developing heart disease but without current symptoms (e.g., certain breeds).
Stage B Dogs with a murmur or other signs of heart disease but without symptoms. This stage is further divided into B1 (no heart enlargement) and B2 (heart enlargement present).
Stage C Dogs with symptoms of heart disease, such as coughing or difficulty breathing, requiring medical treatment.
Stage D Dogs with advanced heart disease that do not respond well to standard treatments and need specialized care.

It might seem like a lot, but all of these steps are crucial for an accurate diagnosis.

How to treat heart disease in dogs

Treatment for heart disease in dogs varies based on the type of condition and its severity. Here are some common treatment options:


Your vet might prescribe some medications, which help manage heart disease symptoms and improve heart function. These can include:

  • Diuretics: Help reduce fluid buildup associated with congestive heart failure, e.g., furosemide.

  • ACE inhibitors: Commonly used for dilated cardiomyopathy (DCM) and mitral valve disease (MVD) to relax blood vessels and reduce the workload on the heart, e.g., benazepril.

  • Beta-blockers: Used to manage arrhythmias and hypertrophic cardiomyopathy (HCM) by slowing down the heart rate and reducing blood pressure, e.g., atenolol.

Your vet will determine the appropriate medication based on your dog's specific needs.

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Diet and exercise

A balanced diet and regular, moderate exercise are essential for managing heart disease in dogs.

Special diets low in sodium and high in essential nutrients can help support heart health, and your vet might advise you to switch to one.

(NOTE: Always consult your vet before making any changes to your dog's diet or exercise routine!)

A middle aged women enjoys a morning run on a beautiful sunny day with her pet, the dogs appreciating the time outside. They jog on a forest trail, the setting sun casting an orange glow on the scene.

Surgical options

In some cases, surgery may be necessary to correct structural heart defects or manage severe cases of heart disease. Surgical procedures can include:

  • Valve repair or replacement: Occasionally performed in cases of mitral valve disease (MVD), though most are medically managed.

  • PDA closure: To correct patent ductus arteriosus (PDA).

  • Balloon valvuloplasty: Used to widen narrowed heart valves, such as in cases of pulmonic stenosis.

These surgeries can significantly improve your dog's quality of life and longevity. Your vet will discuss the best surgical options with you based on your dog's condition.

Managing a dog with heart disease

jack russell terrier runs on a hiking path with its owner, whose legs are visible in the background.

Daily care for a dog with heart disease is much like what you're already doing as a responsible pet parent:

Keep an eye on your dog's symptoms, give medications as prescribed, provide a healthy diet, and keep them appropriately exercised.

Regular vet check-ups are also key to keeping track of the disease and making adjustments.

Prevention and early detection

Preventing heart disease and catching it early can significantly improve your dog's prognosis. Here are some actionable strategies:

Preventative measures

  • Maintain a healthy weight: Aim to keep your dog at a healthy weight to reduce the strain on their heart.

  • Provide a balanced diet: Feed your dog a nutritious diet tailored to support heart health.

  • Schedule regular wellness checkups: Regular vet visits can help detect any early signs of heart disease.

  • Make sure your pet has regular vaccinations and preventative parasite treatments

white fluffy dog being held in vet or nurse professional's arms.

Early detection

  • Know your dog's breed-specific risks: Some breeds are more prone to heart disease. Be aware of these risks and discuss them with your vet.

  • Watch for symptoms: Monitor your dog for signs like coughing, difficulty breathing, or reduced exercise tolerance. If you notice any symptoms, seek veterinary care immediately.

Heart disease in dogs can look incredibly challenging, but with the right care and attention, you can help your furry friend continue to live a fulfilling life for as long as possible.

And if you're looking to take your preventative pet parenting a step further, look into dog insurance!

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Pet insurance is designed to reimburse you for covered accidents and illnesses* your pup might encounter. Just make sure to get it early in life to avoid pre-existing conditions (which are not typically covered).

*see your policy for details.

Leanna Zeibak
Content Manager

Leanna Zeibak is a Content Manager at ManyPets. In her spare time, she paints pet portraits and bakes far too many chocolate chip cookies.