December 2020
- Is my dog having a heart attack?
- What is heart failure?
- What’s the difference between a heart attack and heart failure?
- Why didn’t I know my pet had heart disease before now?
- Why does my pet need so many different pills and what do they all do?
These are questions I commonly hear as a veterinary cardiologist.
The terms 'heart attack' and 'heart failure' are often confused. Heart attacks are rare in dogs and cats. A heart attack happens when the vessels in the heart become blocked by plaque or a blood clot. This results in a sudden lack of blood and oxygen to a portion of the heart muscle, resulting in severe damage to that segment. If a big enough section of the heart is damaged, the patient will go into heart failure or experience sudden death.. Lack of blood flow to the heart can also cause heart rhythm problems that can lead to collapse or sudden death. Coronary artery disease is the most common type of heart disease in people, and the most common cause of death in the US(other than Covid-19). Because heart attacks are rare in pets, cholesterol and fat levels are not generally a concern in dogs and cats.
Heart failure, on the other hand, is common in dogs and cats. Heart failure occurs when the heart can no longer efficiently pump blood through the body. This causes increased backward pressures in the veins and leakage of fluid into the lungs, belly, or limbs. Difficulty breathing, coughing, and abdominal swelling are the most common symptoms of fluid retention and congestive heart failure. Some patients with heart failure also develop lethargy, weakness, exercise intolerance. and even fainting because the heart cannot pump well enough to maintain normal blood pressure. Many different types of heart disease can cause heart failure, including a heart attack; but not all heart attacks cause heart failure.
Early detection of heart disease prior to the onset of heart failure is important since early intervention can help delay symptoms and prolong survival. However, the ability to detect heart disease prior to problems can be difficult. The most common heart disease in dogs is degenerative valve disease (thick, leaky valves) and these patients develop an easily detectable heart murmur. The valves slowly deteriorate, leading to more and more valve leakage, which causes a progressively louder heart murmur. Most dogs that develop heart failure from this disease have had a heart murmur for years.
Other diseases, such as dilated cardiomyopathy, which is common in larger dogs, or hypertrophic cardiomyopathy, the most common heart disease in cats, can be difficult to find before signs of heart failure are obvious. Cats, in particular, are notorious for having “silent cardiomyopathy” (heart disease without a murmur) and can develop heart failure or blood clots seemingly out of the blue. Fluid therapy, steroids and anesthesia can precipitate heart failure in cats with silent disease. This is frustrating for both owners and veterinarians. Fortunately, there is a new screening blood test, called an NT-proBNP, which can help detect the presence of underlying heart disease in pets. This test is especially important in breeds predisposed to cardiomyopathy, such as Maine Coons, Ragdolls, and Persians. Given the high prevalence of silent heart disease in all types of cats, any cat could potentially benefit from having this test performed periodically, especially before anesthesia, steroids or fluid therapy. Dogs predisposed to dilated cardiomyopathy, such as Doberman Pinschers, Boxers, and Irish Wolfhounds, may also benefit from this test. Ultimately, routine wellness visits to your veterinarian for a complete physical examination of your pet and to discuss screening NT-proBNP tests is the best way to catch heart disease before problems develop.
There are many other less common causes of heart failure in dogs and cats, such as congenital heart defects, cardiac tumors, heart scarring, and heartworms. An echocardiogram is needed to sort out the underlying cause and to tailor therapy. Animals with known heart disease should be monitored closely for symptoms and evaluated urgently if they show signs of congestion or fluid buildup. Heart disease is rarely cured, but with appropriate and early therapy, symptoms can be managed from 6 months to a few years with the pet enjoying good quality of life the whole time.
There are 4 main treatment strategies for heart failure. Diuretics, such as lasix or furosemide, help remove fluid and prevent it from accumulating in the lungs or other body areas. Pimobendan (Vetmedin) helps improve the heart strength and efficiency. Enalapril and spironolactone help to protect the heart by blocking some of the negative hormones that become activated with heart disease . Plavix and aspirin are used in cats to reduce the risk for blood clot disease. These medications all have their unique role and work together to keep the pet stable and extend survival. Most pets tolerate heart medications very well. If the patient has negative side effects, the veterinary cardiologist would change either the dose or the medication.. One of the biggest problems managing heart failure is keeping the kidneys happy, and blood work monitoring is important in all cardiac patients.
Hopefully, this blog has helped answer some common questions. Fortunately, there continue to be significant advancements in the treatment of heart failure and most affected pets live with an excellent quality of life in spite of the presence of heart disease.
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