A heart murmur is an abnormal sound produced by the heart due to turbulent blood flow in the heart or large vessels. Heart murmurs typically sound like a swoosh, whoosh, or rasp when the heart beats.
Some heart murmurs are strong enough to be felt by placing a hand on your cat's chest, while others can be heard clearly with a stethoscope and sometimes the veterinarian will need a quiet room to decipher faint murmurs.
What is a Cat Heart Murmur?
Heart murmurs in cats are not always alarming; the severity of the murmur lies in the underlying cause. Some murmurs can be caused by underlying heart disease, structural heart defects, or stress, and in kitties congenital murmurs present at birth usually clear within six months.
Some people assume that a heart murmur generally implies an underlying heart condition. This is not always the case; a murmur can also be caused by other factors like stress.
A heart murmur in cats, therefore, is not an automatic sign of heart disease, so do not be alarmed. The veterinarian will examine your feline friend and determine the appropriate treatment for a heart murmur.
A study has shown that heart murmurs can be detected in healthy cats and about 50% of cats with heart murmurs do not have underlying cardiac disease implying that the murmurs are benign.
What Causes Heart Murmurs in Cats?
Heart murmurs in cats can come and go; they can be heard on one day and not the next day. Stress can lead to such a situation whereby stress raises blood pressure leading to a heart murmur, but when the cat is calm, the cat's murmur fades.
A heart murmur on its own is not a reliable indicator of cardiac disease, therefore follow-up tests are always necessary.
Some heart murmurs are called innocent murmurs. Innocent heart murmur is also called physiologic murmur or functional heart murmur.
Physiologic heart murmurs are soft, benign murmurs that have no impact on the cat's health because there is no underlying heart disease that causes the abnormal noise. Young kittens often have innocent heart murmurs that appear at 6-8 weeks of age and disappear by the time they get to 5 months.
Heart murmurs can also be congenital or acquired. Congenital heart murmurs are present from birth and are typically caused by defects called congenital heart disease like pulmonic stenosis or patent ductus arteriosus. Congenital heart murmurs are often quiet at birth and only become detectable as the kitten grows.
Acquired heart murmur occurs later in life as the cat matures. They can be benign or harmful resulting from heart disease, heart valve damage, or heart muscle disorders (cardiomyopathy).
What Does a Normal Cat's Heartbeat Sound Like?
The heart produces a distinctive sound when it is pumping blood. A normal heartbeat sounds like a "lub-dub" which is caused by the rhythmic closing of the heart valves as blood flows in and out of the heart's chambers.
Turbulent flow in the heart caused by malfunctioning valves, disease, or stress, causes the "whooshing" sound that is differentiable from the normal "lub-dub" heart sound.
How are Heart Murmurs Classified?
Not all heart murmurs in cats are the same, some are loud, others are soft and they also vary in intensity. The three major classifications of heart murmur in cats are based on;
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Intensity: The heart murmur is graded on a scale of I-VI based on loudness, where I is the quiet and soft grade, audible only in one location of the chest. Grade VI is the loudest and is not only clear through a stethoscope but can also be felt when a hand is placed on a cat's chest.
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Configuration: Heart murmurs are also classified based on when they occur during the heart cycle, that is, during contraction and relaxation of the heart.
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Location of the murmur: This is where the murmur is loudest when listening with a stethoscope.
When murmurs are graded based on intensity, it does not mean that heart disease is present, or is less or more severe. Heart murmurs can also be caused by other factors like stress or diseases like anemia that are not heart disease.
The heart murmur intensity scales from I-VI are as follows:
Grade I: This is the first stage of a heart murmur. It is soft, and quiet, and is heard only by a trained ear, otherwise, it is barely audible even when listening with a stethoscope. Veterinarians need to be in a very quiet room to hear this level of heart murmur.
Grade II: These are soft but audible heart murmurs in cats. They can be easily heard with a stethoscope.
Grade III: These are loud intermediate murmurs that can be heard using stethoscopes. They are also the loudest heart murmurs.
Grade IV: These are quite loud murmurs that radiate across the heart. They can be heard on both sides of the chest.
Grade V: These are very loud murmurs that can be heard easily even before the stethoscope touches the heart. They are felt on the chest by a noticeable "trill" vibration.
Grade VI: This is the loudest heart murmur that can be heard easily with the stethoscope not touching the chest and can be felt as a noticeable "trill" vibration on the chest wall.
How Is a Heart Murmur in Cats Diagnosed?
Heart murmurs can be an indicator of underlying heart diseases or structural heart defects. The veterinarian must examine your pet to figure out exactly what is going on and there are various tools like x-rays and echos. Here are some of the diagnosis methods they use;
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Clinical Examination: Your Vet will conduct a physical examination of your pet. He looks for observable clinical signs like breathing, and gum color, conducts examinations using the stethoscope to determine the location of heart murmur, and also asks for a medical history of your pet so all the information you can give is helpful. Incidental murmurs can be found during routine physical examination.
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Blood tests: These blood tests examine the substances in your pet's blood. The tests can determine glucose levels protein levels, hydration, and some diseases. Protein levels can drop when your pet has some heart disease, therefore the tests are good to help your vet pinpoint exactly what is wrong.
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ECG or electrocardiogram: An echo is a diagnostic, detailed ultrasound examination, that creates an image of the heart and the blood vessels around it. Echos measure the heart's electrical activity, which varies depending on rhythm, heart rate, chamber size, and orientation, all of which help to determine the location of the murmur. Echos are used when an abnormal heart rhythm is noticed.
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X-rays: X-ray radiation generates images of tissues and structures inside the body. X-rays paint the image of the shape, size, and position of the heart in the chest.
Heart Murmur Treatment in Cats
Vets do not treat a heart murmur itself because it is a symptom of an underlying condition. There are many causes of heart murmur in cats including severe heart disease, anemia, and congenital heart defects therefore the treatment plan will depend on the underlying cause and severity.
Innocent or benign murmurs do not particularly require treatment, pet owners are simply advised to take their cats for periodic examination and monitoring in case any problem develops.
Some of the treatment plans for severe murmur include specialized diets, medications, supportive care, or a combination of these. Other conditions require surgery, for example, PDA or septal defect requires surgery to close the ductus arteriosus and septal defects need surgery to close the hole between the ventricles.
Other underlying conditions like anemia when they are resolved also help to clear the heart murmurs. Incidental murmurs caused by stress are also clear after the cat is well and their heart rate drops. In this case, the vet will simply monitor your feline friend.
The vets closely monitor your pet even after treatment to check if the condition progresses. Prognosis ranges from excellent to grave depending on whether the heart murmur is benign or severe and the treatment needed.
Conclusion
A heart murmur is common in cats and is not always a cause for alarm. Some murmurs are benign and others are severe while some are present at birth but others are acquired as the cat gets older. These murmurs always point to an underlying condition and that is what vets treat.
If your cat has heart murmur, do not worry, all hope is not lost. There are various treatment options including medication, surgery, proper nutrition & diet and supportive care. The vet will always advise you on the most suitable treatment plan after examining your cat and doing some tests. With propper monitoring and frequent examination, your fekline friend can live a happy long life.
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