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February 7, 2017 – Heart disease is a common problem in dogs and, like people, can be caused by a variety of underlying diseases including heart valve degeneration, irregular heart rate and rhythm (arrhythmia), and heart muscle disease. In spite of the many types of heart diseases affecting dogs, most share common signs that can alert owners to a problem.

Five common signs of heart disease in dogs include:

  1. Cough – Dogs with heart disease have coughs that don’t resolve within a few days. Dogs with heart disease cough for many reasons. Fluid can begin to accumulate in the lungs because the heart isn’t pumping efficiently. This leads to a “back-up” of blood in the lungs, which can result in fluid leaking out of blood vessels and accumulating in lung tissue, resulting in cough. Some heart diseases 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.
  2. Fainting or collapse – When heart function decreases, 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 is usually triggered by exercise, although sometimes coughing can trigger an episode.
  3. 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.
  4. 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.
  5. Behavior change – Many behavior changes can be seen 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 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 include:

  • Chest X-ray – X-rays remain a good way to assess heart size, and remain one of the best ways to assess fluid build-up in and around the lungs.
  • Electrocardiogram (ECG) – An ECG is the best way to detect an arrhythmia. Sometimes a veterinarian will have a dog wear a Holter monitor to look for irregular heartbeats over several days while a dog is at home
  • Echocardiogram – An echocardiogram is an ultrasound of the heart. This non-invasive test has revolutionized the diagnosis of heart diseases in both people and dogs. An echocardiogram performed by a skilled veterinarian can provide important information not only about disease, but also provide measurements to assess therapy.

Although heart disease in dogs can be serious, many treatment options are available to help our dogs with heart disease not just control signs, 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 four-legged friend.

Morris Animal Foundation has been funding canine heart disease studies since 1960. Our studies have covered cardiac issues from understanding canine ECGs to our most recent study looking at the genetic basis of heart valve disease in dogs.

We’re also collecting data on heart disease in dogs in our Golden Retriever Lifetime Study. Understanding how heart disease develops over time is important information we can gather through monitoring this large cohort, something that's not 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.