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Updated February 10, 2022 – Heart disease is a common problem in dogs and, as in people, can be caused by a variety of underlying conditions, including heart valve degeneration, irregular heart rate and rhythm (arrhythmia), and heart muscle disease. Despite the many types of heart diseases affecting dogs, most share common signs that can alert owners to a problem.

Persistent Cough – If your dog has a cough that doesn’t clear up in a few days, heart disease may be the culprit. Dogs with heart disease cough for many reasons. In some dogs, fluid can accumulate in the lungs when the heart isn’t pumping efficiently. This backup of blood in the lungs can result in fluid leaking out of blood vessels and accumulating in lung tissue, resulting in cough. Other dogs may have heart diseases that lead to heart enlargement. The enlarged heart can press on airways and stimulate coughing. Any persistent cough that lasts more than a few days should be checked by a veterinarian.

Fainting or Collapse – When heart function is less than optimal, vital organs such as the brain can become deprived of nutrients, especially oxygen. Blood flow to the brain can be compromised in dogs with heart disease, leading to fainting (syncope) or collapse. Syncope and collapse in dogs with heart disease usually are triggered by exercise, although sometimes coughing can trigger an episode.

Difficulty Breathing – Dogs with heart disease often will have difficulty breathing (dyspnea). A dog may breathe more rapidly, or with more force. Some dogs will sit or stand with their legs wide apart and with their neck stretched out. Dogs with severe heart disease have more trouble breathing when lying down, and will often sit or stand for long periods of time.

Fatigue, Inability to Exercise – Dogs with heart disease will tire out more quickly on walks and during exercise. They may sleep or rest more than usual.

Behavior Changes – Pet owners also may see behavior changes in dogs with heart disease, including poor appetite, isolation and a reluctance to play or engage in previously pleasurable activities.

Signs of heart disease can mimic those seen with other diseases such as arthritis, seizures and chronic lung disease. Your veterinarian can narrow down the diagnostic possibilities with a good history and diagnostic tests.

Tests Helpful in Heart Disease Diagnosis

Chest X-ray – X-rays remain a good way to assess heart size, and one of the best methods to assess fluid buildup in and around the lungs.

Electrocardiogram (ECG) – An ECG is the best way to detect an arrhythmia or abnormal heartbeat. Sometimes a veterinarian will have a dog wear a Holter monitor, a portable device that continuously monitors the electrical activity of the heart, to look for irregular heartbeats over several days while a dog is at home.

Echocardiogram – An echocardiogram is an ultrasound of the heart. This noninvasive test has revolutionized the diagnosis of heart diseases in both people and dogs. An echocardiogram performed by a skilled veterinarian can provide valuable information not only about disease, but also provide measurements to assess therapy.

Blood Tests – Although not as commonly used in dogs as in people, there are new tests for dogs that measure cardiac biomarkers in the blood. The most commonly measured biomarker is the protein NT-proBNP, which is elevated in dogs with advanced heart disease.

Although heart disease in dogs can be serious, many treatment options are available to help not only control symptoms, but live a higher quality life. Diet therapy, modification of activity, and therapeutics are all strategies used to treat heart disease in dogs. Your veterinarian can help select which therapies are best for your furry friend.

How We Are Helping

Morris Animal Foundation has been funding canine heart disease studies since 1960. Our research has covered cardiac issues from understanding canine ECGs to our most recent studies evaluating new medications, including a new heart failure drug.

We’re also collecting data on heart disease in dogs in our Golden Retriever Lifetime Study. Understanding how heart disease develops over time is valuable information we can gather through monitoring this large cohort, something that hasn’t been done before in the United States. Our study participants will help us gain a better understanding of not only the natural course of heart disease progression, but possibly identify risk factors associated with the development of heart problems.