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Heart Disease in Dogs
Heart failure is a condition in which the heart is unable to circulate blood throughout the body in a normal fashion. In dogs, two types of heart disease may lead to heart failure. The most common type of heart disease in dogs is caused by a malfunctioning (or leaky) valve in the heart. Another form of heart disease, called cardiomyopathy, is caused by a defect in the muscles of the heart. Although these two syndromes develop in different fashions, both often lead to the same result: heart failure.
In dogs, heart disease is almost exclusively linked to hereditary factors and individual characteristics of each animal. Although obesity exacerbates preexisting heart disease, in dogs lifestyle, diet, and exercise usually do not play a significant role in causing heart problems.
Dogs with mild heart disease often show no symptoms. Heart disease may develop over a period of years before any irregularities are noticed. As heart disease progresses to heart failure, the following symptoms may occur.
- Dogs with heart failure may be weak, or display a disinclination to run, play, walk, or exercise for extended periods of time.
- Coughing commonly occurs in dogs with heart failure. Coughing may be especially pronounced at night, in the morning, and during activity or excitement.
- Dogs suffering from heart failure may experience rapid breathing or difficulty breathing. Any dog that has difficulty breathing should be assessed by a veterinarian immediately.
- Many dogs with heart disease have heart murmurs that can be detected by veterinarians.
- Heart failure may lead to blue or purple gums in affected individuals.
- Dogs with severe heart failure are prone to collapsing or suddenly losing consciousness.
- In some cases, dogs with heart failure will develop distended abdomens.
- Heart failure is believed to be largely hereditary in dogs. Many breeds are predisposed to heart disease. Miniature Poodles, Toy Poodles, Teacup Poodles, Miniature Schnauzers, Chihuahuas, Fox Terriers, Cocker Spaniels, Boston Terriers, and Cavalier King Charles Spaniels are predisposed to heart disease caused by leaking valves. Boxers and Doberman Pinschers are predisposed to cardiomyopathy.
- Male dogs suffer higher rates of heart disease than female dogs.
- Age is a significant risk factor. Older dogs are at greater risk than puppies and young adults.
- Dental disease or chronic skin infections can exacerbate heart disease and heart failure.
Heart disease in dogs is progressive. However, the rate of progression varies, and in some dogs it is very slow. Many dogs diagnosed with heart disease never develop symptoms heart failure.
Dogs with heart failure have reduced tolerance for heat, exercise, and stress.
Heart failure may cause dogs to suffer complications during anesthesia. Caution must be used when anesthetizing or performing diagnostic procedures on dogs with heart disease.
Severe heart failure may lead to collapse or sudden death.
Finding a heart murmur on physical examinations often leads to the suspicion of heart disease. To fully characterize the presence and extent of heart disease, veterinarians usually perform diagnostic tests including X-rays of the heart, ultrasound of the heart (also known as echocardiography), and electrocardiography (also known as ECG or EKG). A blood test, called pro-BNP, may aid in the diagnosis of heart disease in dogs.
Because dogs with heart failure have low tolerances for stress, some tests may be omitted in frightened or nervous dogs.
- Dogs with heart failure should avoid stress, heat, and strenuous activity.
- A number of medications are used to treat heart disease and heart failure. Enalapril and benazepril are related medications that may be prescribed for dogs with heart disease, even if heart failure is not present. Furosemide (Lasix®) and related medicines such as spironolactone are frequently used to treat heart failure.
- Dogs with heart failure may benefit from specially designed diets that are low in sodium.
- Valve replacement is not commonly performed in dogs. However, it may be a promising treatment for many cases of heart disease in the future.
The goals of treatment are improved symptoms and slowed progression of the heart disease. Clinical response to therapy is a critical measure of the success of treatment.
Most dogs with heart disease require periodic follow-up X-rays and ultrasound examinations.
Dogs with heart disease should undergo regular blood and urine tests to assess the function of other organs in the body. This is especially important for dogs that receive medications as part of their treatment protocols.
Dogs with heart failure may suffer episodes of severe symptoms interspersed between periods in which they are symptom-free.
Many dogs with heart disease never develop heart failure.
In some dogs, the first symptom of heart disease may be collapse or sudden death.
Caution must be exercised when anesthetizing dogs with heart disease. However, dogs with heart disease often undergo anesthesia without incident. Particularly for dogs with periodontal disease, the benefits of anesthesia for dental work may outweigh the risks.
Because heart failure leads to decreased tolerance for stress, some dogs suffer complications during diagnostic procedures such as X-rays or ultrasound examinations. If a dog is thought to be at especially high risk for these complications, some tests may be omitted.
Copyright © Eric Barchas, DVM All rights reserved.
The contents of this page are provided for general informational purposes only. Under no circumstances should this page be substituted for professional consultation with a veterinarian.