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Heart Disease in Dogs

What Is Heart Disease in Dogs?

Heart disease is a prevalent issue among aging dogs, affecting many of them as they grow older. As the primary function of the heart is to circulate blood throughout the body, any complications with this vital organ can lead to serious consequences.

Understanding the various types of heart disease commonly observed in dogs is essential for recognizing potential issues early on. It’s crucial to seek veterinary attention for dogs displaying signs of heart disease, as early intervention offers the best chance of successful treatment. Additionally, long-term monitoring by a veterinary cardiologist may be necessary for managing the condition effectively.

Most Common Heart Diseases in Dogs

  • Heart Valve Disease: The heart comprises four valves responsible for directing blood flow. Any defects or damage to these valves can disrupt smooth blood flow, leading to a heart murmur and potentially congestive heart failure. The most common form, myxomatous mitral valve degeneration (MMVD), typically affects older, small-breed dogs.
  • Myocardial (Heart Muscle) Disease: This occurs when the heart muscle deteriorates, causing thinning and reducing its ability to pump blood effectively. Dilated cardiomyopathy (DCM) is a common manifestation where the heart muscle weakens, while hypertrophic cardiomyopathy (HCM) involves thickening of the heart muscle, hindering normal blood filling.
  • Heartworm Disease: Transmitted through mosquito bites, heartworms infest the heart and larger lung blood vessels, causing inflammation and blockages that impede blood flow from the heart to the lungs.
  • Arrhythmias: Irregular heart rhythms, whether too slow, too fast, or irregular, can hamper blood circulation to the lungs and the rest of the body.
  • Shunts: Abnormal vessels or holes in and around the heart disrupt normal blood circulation. Most instances, like patent ductus arteriosus and ventricular septal defects, are congenital.
  • Stenosis: Some puppies are born with narrowed areas around their heart valves, obstructing blood flow. Common forms include pulmonic stenosis and subaortic stenosis.
  • Pericardial Disease: The pericardium, which envelops the heart, may become rigid or accumulate fluid (often blood or air) in the space between the pericardium and the heart, hindering effective heartbeats.
  • Congestive Heart Failure (CHF): A consequence of various heart diseases, CHF arises when the heart fails to pump blood adequately to meet the body’s needs. Fluid may accumulate in or around the lungs, abdomen, or other tissues due to leaking blood vessels.


Various types of heart disease in dogs may present with different symptoms, but typically, affected dogs exhibit a combination of the following signs:

  • Coughing
  • Breathing difficulties
  • Easily becoming fatigued
  • Weakness
  • Weight loss
  • Diarrhea
  • Bluish or grayish gums
  • Unusual swellings (in legs or abdomen, for instance)
  • Sleeping difficulties
  • Fainting
  • Collapsing

While these symptoms can also indicate other health issues, such as lung diseases, it’s crucial to promptly seek veterinary attention for an accurate diagnosis.


The causes of heart disease in dogs can be classified as congenital, present from birth, or acquired, developing later in life. Symptoms of congenital heart disease typically manifest in puppies or young adult dogs, often influenced by genetic factors. Acquired heart disease may not show noticeable signs until a dog reaches middle age or older, although genetics and breed predisposition still play significant roles. Overweight dogs may face an elevated risk of experiencing more severe symptoms of heart disease.

Nutrition also plays a role in certain types of heart disease. For instance, diets lacking the amino acid taurine can increase the likelihood of dilated cardiomyopathy. Some breeds, such as Golden Retrievers, may have higher dietary taurine requirements.

Recently, a particular form of dilated cardiomyopathy has been linked to specific types of dog food (such as boutique, exotic, and grain-free varieties), although taurine deficiency does not seem to be the cause, and a definitive cause has yet to be identified.


The initial step in diagnosing heart disease in dogs involves a comprehensive physical examination by a veterinarian. Using a stethoscope, the vet listens to the dog’s heart and lungs, checking for irregular rhythms and sounds such as murmurs or lung crackles indicating fluid accumulation.

Additionally, the vet assesses the dog’s pulse and examines for signs of fluid retention in the abdomen and other tissues. Owners should be prepared to provide information about their dog’s health history and any observed symptoms at home. In some cases, a veterinary cardiologist may be consulted for further evaluation.

Diagnostic testing is typically required to confirm heart disease, which may include:

  • Chest X-rays to assess the heart’s size and shape, as well as to examine the lungs and other chest structures.
  • Electrocardiogram (ECG) to detect abnormalities in heart rhythm.
  • Echocardiogram, an ultrasound examination, to observe blood flow within the heart and assess the condition of heart valves and muscles.
  • Heartworm tests.
  • Blood pressure measurement.

Depending on the specific case, additional laboratory work and diagnostic tests may be necessary to provide a comprehensive evaluation of the dog’s condition.


Various treatments are available for heart disease in dogs, with the primary focus being on addressing the underlying cause whenever feasible. In cases where the heart disease can be cured, symptoms may completely resolve. For instance:

  • Adult heartworms can be eliminated using injections of melarsomine, a derivative of arsenic.
  • Certain types of arrhythmias can be managed with pacemakers or surgical interventions.
  • Surgery may be considered to correct cardiac shunts, stenosis, or specific valvular or pericardial conditions.

More commonly, heart disease in dogs is managed through medication, which can:

  • Enhance the heart’s efficiency in pumping blood (e.g., enalapril and pimobendan).
  • Assist in removing excess fluid from the body (e.g., furosemide or spironolactone).
  • Normalize heart rhythm (e.g., atenolol, sotalol, propranolol, amiodarone, diltiazem, and digoxin).

Additionally, dietary modifications may be recommended by your veterinarian. For instance:

  • Weight loss or supplementation with nutritional additives like taurine may benefit some dogs with heart disease.
  • Feeding a low-sodium diet might help reduce fluid retention in cases of congestive heart failure.

Living and Management

When diagnosed early and managed effectively, dogs with heart disease often enjoy many more years of happy life.

Nevertheless, in severe cases of heart disease or when congestive heart failure develops, the prognosis becomes more uncertain. Eventually, there may be a point where available treatments are unable to sustain the dog’s quality of life.

Heart Disease in Dogs FAQs

Are dogs with heart disease in pain?

Heart disease typically doesn’t induce pain in dogs, but it may lead to other forms of discomfort such as breathing difficulties, persistent coughing, and profound weakness. Veterinary interventions can significantly improve the well-being of dogs with heart disease.

What is the most prevalent type of heart disease in dogs?

As dogs age, small breeds commonly experience issues with leaky heart valves, while large breeds are more prone to heart muscle functioning problems.

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