Heart disease is an umbrella term that encompasses many different conditions affecting the heart's structure and function. Understanding the specific type your dog has been diagnosed with is important because each type has its own progression, treatment approach, and prognosis.

The most common forms of heart disease in dogs include:

• Mitral valve disease (MVD): This is the single most common heart disease in dogs, accounting for approximately 75% of all canine heart disease cases. It occurs when the mitral valve, which separates the left atrium from the left ventricle, degenerates over time and begins to leak. It is most prevalent in small to medium breeds such as Cavalier King Charles Spaniels, Dachshunds, Miniature Poodles, and Chihuahuas. It develops gradually and may take years to progress to heart failure.
• Dilated cardiomyopathy (DCM): In this condition, the heart muscle weakens and the heart chambers enlarge, reducing the heart's ability to pump blood effectively. DCM primarily affects large and giant breed dogs, including Doberman Pinschers, Great Danes, Irish Wolfhounds, and Boxers. It can progress more rapidly than MVD and sometimes presents with sudden, severe symptoms.
• Congestive heart failure (CHF): CHF is not a disease itself but rather the end result of progressive heart disease. It occurs when the heart can no longer pump blood efficiently enough to meet the body's needs, causing fluid to accumulate in the lungs (left-sided failure) or abdomen (right-sided failure). CHF can result from MVD, DCM, or other heart conditions.

Less common forms include pericardial disease (fluid around the heart), congenital heart defects (present from birth), and arrhythmias (irregular heart rhythms). Your veterinarian or veterinary cardiologist can determine the specific type and stage through diagnostic testing.

Heart disease in dogs can develop silently for months or even years before symptoms become apparent. In many cases, a veterinarian first detects a heart murmur during a routine physical examination before the owner has noticed anything wrong at home. This is one of many reasons why regular wellness visits are so important.

As heart disease progresses, the following signs may develop:

• Coughing: A persistent cough, especially at night or after rest, is one of the most common early signs. This occurs as the enlarging heart presses on the airways or fluid begins accumulating in the lungs.
• Exercise intolerance: Your dog may tire more easily during walks or play, seem reluctant to exercise, or need frequent rest breaks during activities they previously handled easily.
• Rapid or labored breathing: An increased breathing rate, especially at rest (normal is under 30 breaths per minute while sleeping), can indicate fluid buildup in the lungs.
• Fainting or collapse: Episodes of sudden weakness, collapse, or loss of consciousness can occur when the heart cannot maintain adequate blood flow to the brain. This is more common with certain arrhythmias and advanced DCM.
• Distended abdomen: A swollen belly can indicate fluid accumulation due to right-sided heart failure.
• Decreased appetite and weight loss: As heart disease progresses, dogs may eat less and gradually lose weight and muscle mass.
• Restlessness at night: Difficulty settling or breathing comfortably when lying down, particularly lying flat, can indicate worsening heart failure.

One of the most useful things you can do at home is monitor your dog's resting respiratory rate. Count the number of breaths your dog takes in 60 seconds while they are sleeping or fully relaxed. A consistent resting rate above 30 breaths per minute, or any significant increase from your dog's normal baseline, warrants a veterinary visit. Several smartphone apps can help you track this over time.

Diagnosing heart disease accurately requires several tests, as the specific type and stage determine the treatment approach. Your veterinarian may recommend some or all of the following:

• Physical examination: Listening to the heart with a stethoscope can reveal murmurs, arrhythmias, and abnormal lung sounds.
• Chest X-rays (radiographs): These show the size and shape of the heart and whether fluid is accumulating in the lungs.
• Echocardiogram (heart ultrasound): This is the gold standard for diagnosing heart disease. It allows the veterinarian to visualize the heart's chambers, valves, and blood flow in real time, and to measure how well the heart is pumping.
• Electrocardiogram (ECG): This records the heart's electrical activity and is essential for diagnosing arrhythmias.
• Blood tests: Cardiac biomarkers (such as NT-proBNP and troponin) and kidney function tests help assess severity and guide treatment.

Treatment depends on the type and stage of heart disease. In early stages, when no symptoms are present, your veterinarian may recommend monitoring with periodic rechecks. For mitral valve disease, the EPIC trial demonstrated that starting the medication pimobendan at a specific stage before heart failure develops significantly delays the onset of symptoms.

Once heart failure develops, treatment typically involves a combination of medications including diuretics (such as furosemide) to remove excess fluid, pimobendan to strengthen heart contractions, and ACE inhibitors to reduce the workload on the heart. Additional medications may be added depending on the individual case. Dietary modifications, including sodium restriction, may also be recommended.

Regular follow-up visits are essential to monitor disease progression and adjust medications. Many dogs respond very well to treatment and can enjoy a good quality of life for an extended period after diagnosis.

Managing heart disease in dogs is a long-term commitment that requires close partnership between you and your veterinary team. Once your dog is on heart medications, consistency and monitoring become part of your daily routine.

Common heart medications and their roles include:

• Pimobendan (Vetmedin): This medication strengthens the heart's contractions and opens blood vessels, reducing the heart's workload. It is typically given twice daily, 1 hour before food for optimal absorption.
• Furosemide (Lasix): A diuretic that removes excess fluid from the lungs and body. Dosing may need to be adjusted frequently as the disease progresses. Ensure your dog always has access to fresh water, as diuretics increase thirst and urination.
• Enalapril or Benazepril (ACE inhibitors): These medications relax blood vessels and reduce blood pressure, making it easier for the heart to pump blood.
• Spironolactone: A mild diuretic that also has heart-protective properties. It is often used in combination with furosemide.

Beyond medications, daily management includes monitoring your dog's resting respiratory rate, keeping a consistent daily routine, providing moderate (not strenuous) exercise as recommended by your vet, and maintaining a healthy body weight. Obesity puts additional strain on an already compromised heart.

Keep a journal or use a tracking app to record your dog's respiratory rate, appetite, energy level, and any coughing episodes. This information is invaluable at veterinary visits and helps detect subtle changes early. Your veterinary team may want to recheck bloodwork and imaging every 3-6 months, or more frequently if medications are being adjusted.

While managing a dog with heart disease requires effort and vigilance, many owners find that with the right medication protocol, their dogs continue to enjoy walks, play, and the everyday moments that make life together meaningful.

Despite the best medical management, heart disease is progressive, and there will come a time when your dog's quality of life begins to decline. This is one of the hardest aspects of living with a dog with heart disease, the knowledge that the condition will eventually advance beyond what medications can control.

Signs that heart disease is entering its final stages include:

• Increasing cough frequency and severity despite medication adjustments
• Persistent difficulty breathing, especially at rest
• Resting respiratory rate consistently elevated above 40 breaths per minute despite diuretics
• Loss of appetite and progressive weight loss
• Recurring episodes of collapse or fainting
• Fluid accumulation (in the lungs or abdomen) that returns quickly after treatment
• Overall withdrawal, loss of interest in family, food, and activities that once brought joy

Our Quality of Life Calculator can help you track your dog's daily well-being and identify trends that might not be obvious day to day. It provides an objective framework for assessing whether your dog is still having more good days than bad.

When medications are no longer able to keep your dog comfortable, the kindest conversation to have is an honest one with your veterinarian about your dog's quality of life. Many owners describe a sense of relief after making the decision, knowing that they chose their dog's comfort above all else.

There is no perfect time to say goodbye, and waiting for the "right moment" can sometimes mean waiting too long. Many veterinarians advise that it is better to be a week too early than a day too late. Whatever you decide, know that loving your dog enough to prioritize their comfort over your own desire to keep them is one of the most selfless acts of love there is.