When doing a thorough physical exam, we sometimes hear heart murmurs in pets. Often, pet parents are worried when we tell them. I want to shed some light on the subject to help navigate through the good, the bad and the ugly regarding heart murmurs. Hearing a heart murmur is not a diagnosis of any particular type of heart disease. A heart murmur is simply an abnormal sound made by the heart when listening with a stethoscope. Murmurs are extra heart vibrations. The sound is created from a disturbance in the blood flow that produces a “swooshing” sound between the normal “lub-dub” heart sounds.
Hearing a murmur during a physical exam is no reason to panic. However, a heart murmur is a reason to discuss heart disease and what it may mean for your pet. Many dogs and cats with heart murmurs will live long, happy, healthy lives. They may never need treatment for heart disease. For some, the murmur can indicate something more serious. Further testing can determine whether your pet needs treatment.
Types of Heart Murmurs in Pets
First, we’ll talk about the grade of the heart murmur. Murmur grading is a way to describe the loudness, the intensity and the number of locations where we hear the murmur. The louder, more intense, and the more locations on the chest (i.e., left side, underside and right side of the chest) where we hear the murmur, the higher the grade.
Heart murmurs are graded on a scale from 1 to 6, with 1 being very soft and often difficult to hear and 6 being very loud. A vet can hear a 6 anywhere you put the stethoscope on the animal’s chest. You can feel a grade 6 murmur as a vibration when you place your hand over your pet’s heart. Higher murmur grades can indicate more cause for concern. However, grade does not always correlate with the severity of the underlying heart disease. For instance, a cat with a grade 1 can have severe heart disease (i.e., cardiomyopathy). Meanwhile, another cat with a grade 5 murmur may have minimal heart abnormalities that would never cause any clinical signs or warrant any kind of heart treatment.
Causes of Heart Murmurs
Heart murmurs can result from actual damage or changes within the heart, or from causes that are unrelated to primary heart disease. The cause of the sounds can vary because murmurs are caused by turbulent blood flow through the the heart itself. The heart is designed to pump blood forward through the body in one direction. Faulty valves, abnormal stretching of the heart muscles, dilated heart chambers, holes in the heart walls, narrowing of the arteries or veins, or a tumor or other structural abnormality will allow some of the blood to go in the wrong direction, creating turbulence and resulting in the murmur “swooshing” noise.
Non-Heart Related Causes
Sometimes innocent murmurs, which are benign and not associated with heart disease, can occur in a young animal under the age of 15 weeks. Murmurs also happen in a pet who is overly excited, anxious or panting. Sometimes, anemia or other non-heart conditions that may cause the heart to speed up temporarily. For example, anemia occurs when there is not enough iron in the blood, but that can affect the heart. These murmurs are usually soft, intermittent, and often resolve as the puppy or kitten grows, once the pet calms down or after the cause of the anemia is corrected.
Some animals are born with a congenital heart murmur, due to structural defects within the heart. Usually, these murmurs are found during puppy and kitten exams. Sometimes these murmurs can only be detected later in life. The severity and causes of congenital murmurs vary widely. We recommend baseline testing for puppies or kittens with a heart murmur that is greater than a grade 2 and still present after 5 to 6 months of age.
An acquired murmur develops later in life. These murmurs can be from a wide variety of causes and can range from being incidental to very serious. We recommend baseline testing to investigate every heart murmur. That said, many cases do not warrant a full cardiac workup.
If we detect the murmur on a routine examination in an otherwise happy, healthy animal, many pet owners will elect to monitor their fur baby for signs of something more serious.
If the murmur is already affecting your pet, we will recommend a series of tests based on your pet’s specific signs and symptoms. Some tests should always be performed before scheduling a procedure requiring anesthesia for animals with a heart murmur.
Testing for Heart Conditions
We recommend several tests to help determine the cause and the severity of the condition causing the heart murmur:
- A complete blood and urine panel. This test will help us check for anemia, infections, kidney disease, liver disease, thyroid disease and other medical abnormalities that can cause or worsen heart disease.
- The Cardiopet ProBNP is a simple blood test that checks for the presence of a hormone released as the heart muscle stretches. Stretching can happen due to a heart being overworked from structural defect or damage. We will investigate any abnormalities found on the blood panel or ProBNP test.
- Simple, non-invasive and relatively inexpensive cardiac tests. These include blood pressure measurement, electrocardiography (ECG or EKG) and chest x-rays. Based on the results and your pet’s clinical signs, more advanced testing may be warranted. Advanced tests include an echocardiogram (an ultrasound of the heart), Holter monitor and an evaluation by a veterinary cardiologist.
The tests will shed light on the cause, severity and the need for treatment, so we can give you a more accurate prognosis for your pet’s quality of life and expected life span.
Treatment for a heart murmur itself is not warranted. What we do for the underlying heart disease would be tailored to the pet’s symptoms and cause of the murmur. You pet may need dietary changes, exercise restrictions and medication. We look at many factors, including whether your pet will benefit from the treatment, the pet’s acceptance of the treatment, the cost of treatment and the owner’s commitment to providing the level of care recommended.
We recommend not breeding any animal with a heart murmur. Breeding can exacerbate heart disease. Animals with heart disease may pass the condition to their offspring. Animals with heart disease should maintain a healthy weight. They should be monitored closely and taken to a veterinarian at the first sign that something is off. They need regular examinations twice a year with basic blood testing. They should maintain healthy oral hygiene, as the inflammation and infection associated with dental disease can exacerbate heart disease.
In summary, diagnosis of a heart murmur in your pet, young or old, can be scary. It is in no way a death sentence for most pets. Take a deep breath, then discuss your pet’s history, symptoms, risks, lifestyle and your concerns with your veterinarian. We will run basic tests, but monitoring your otherwise healthy pet is also an option. The key to keeping your pet happy and healthy for as long as possible is close monitoring for signs that they may have heart disease.
Signs that your pet may have worsening heart disease include exercise intolerance, lethargy, weakness, limping or loss of use of their back legs (especially in cats), decreased appetite, weight loss, increased breathing rates or effort, coughing or anything else that seems unusual for your pet. Noticing any of the above symptoms warrants an immediate trip to your veterinarian or emergency veterinarian, if it is after hours. Know that heart disease can be treated and managed in most pets. However, early detection, prevention and treatment are crucial.
Helping your pet have a happy, healthy heart is our commitment to you and your pet!! Happy Valentine’s month from Harmony Animal Hospital!!