Understanding the Main Types of Heart Disease in Pets

A plain guide to the most common heart conditions that affect our dogs and cats, how they manifest, and why early detection matters for their well-being.

By Garret Merkley · Explainer · Jun 26, 2026

Branched from Heart Disease and Endocarditis in Pets: The Oral-Cardiac Connection Explained

Quick take

Heart disease in pets means their heart isn't working as it should, either structurally or functionally.
It can be congenital (present from birth) or acquired (develops later in life).
Common types include issues with heart valves, the heart muscle itself, or the electrical rhythm.
Early detection through regular vet check-ups and symptom awareness is key to managing the condition and improving quality of life.

Heart disease in pets refers to any condition that impairs the heart's ability to pump blood effectively throughout the body. This can involve problems with the heart's structure, such as its valves or muscle walls, or its electrical system, which controls the rhythm of heartbeats. When the heart can't perform its job properly, it impacts oxygen and nutrient delivery to organs, leading to a range of symptoms and health issues.

Congenital vs. Acquired Heart Disease

Heart conditions in pets generally fall into two broad categories: congenital and acquired. Congenital heart diseases are present at birth, meaning the pet was born with a heart defect. These are often genetic and can range from minor issues to severe malformations that impact a young animal's development. Acquired heart diseases, on the other hand, develop over time, typically in adult or senior pets, due to factors like aging, infection, diet, or other underlying health problems.

Common Acquired Heart Conditions and How They Work

Most heart disease seen in adult pets is acquired. Understanding the main types helps us recognize what might be happening within our companion animals.

Valvular Disease

This is the most common type of heart disease in dogs, especially smaller breeds. It primarily involves the heart valves, which are like one-way doors that ensure blood flows in the correct direction through the heart chambers. Over time, these valves, particularly the mitral valve, can thicken and degenerate, becoming leaky. This leakage, known as regurgitation, causes blood to flow backward, forcing the heart to work harder to maintain circulation. This extra strain can lead to an enlarged heart and eventually heart failure.

Myocardial Disease (Heart Muscle Disease)

Myocardial diseases affect the heart muscle itself, making it either too weak or too thick to pump blood efficiently. The two main forms are:

**Dilated Cardiomyopathy (DCM):** More common in large and giant breed dogs (e.g., Doberman Pinschers, Great Danes), DCM causes the heart chambers to enlarge and the heart muscle to become thin and weak. This reduces the heart's ability to contract forcefully and pump blood out to the body.
**Hypertrophic Cardiomyopathy (HCM):** This is the most common heart disease in cats. HCM involves a thickening of the heart muscle walls, particularly the left ventricle. This thickening makes the heart chambers smaller and stiffer, reducing the amount of blood they can hold and effectively pump. It also impedes the heart's ability to relax and fill properly.

Arrhythmias (Irregular Heartbeats)

Arrhythmias are abnormalities in the heart's electrical activity, leading to an irregular heart rhythm. The heart might beat too fast (tachycardia), too slow (bradycardia), or irregularly. These electrical disruptions can compromise the heart's pumping efficiency, leading to dizziness, weakness, or even collapse. Arrhythmias can occur as a primary problem or secondary to other heart conditions or systemic illnesses.

Why Early Detection and Management Matter

Recognizing the signs of heart disease early is crucial for extending and improving a pet's quality of life. While many forms of heart disease are progressive and cannot be cured, they can often be managed effectively with medication, dietary changes, and lifestyle adjustments. Regular veterinary check-ups are vital, especially for breeds predisposed to heart conditions, as a vet can detect subtle changes like heart murmurs or arrhythmias before symptoms become obvious. Proactive management can slow the progression of the disease, alleviate symptoms, and help your pet live more comfortably for longer.

What are the most common signs of heart disease in pets?

Common signs include coughing (especially a soft, persistent cough), lethargy or reduced exercise tolerance, difficulty breathing or panting more than usual, weakness, fainting episodes, and a swollen abdomen (due to fluid buildup).

Can heart disease be prevented in pets?

While not all heart disease is preventable, maintaining a healthy weight, providing a balanced diet, ensuring regular exercise, and consistent dental care can reduce risk factors for some acquired conditions. Genetic predispositions for congenital issues cannot be prevented, but early screening can help identify at-risk animals.

How is heart disease diagnosed in pets?

Diagnosis typically involves a physical exam, listening for heart murmurs or abnormal rhythms, chest X-rays to check heart size and fluid in the lungs, an echocardiogram (ultrasound of the heart) to visualize its structure and function, and an electrocardiogram (ECG) to assess electrical activity.

Is treatment for pet heart disease expensive?

The cost of treatment can vary widely depending on the type and severity of the disease, required medications, and specialist consultations. While ongoing management can be an investment, many owners find the benefits in their pet's quality of life to be well worth it. Pet insurance can also help mitigate these costs.