Download Heart Murmurs - Pride Veterinary Centre

My pet has a heart murmur – now what?
When your veterinary surgeon listens to your pet’s heart, normally
there are two distinct sounds to be heard. Often these sounds are
referred to as “lub” and “dub”. A heart murmur is an abnormal
additional heart sound caused by turbulent blood flow that can be
heard between the “lub” and the “dub”.
The presence of a heart murmur may be one of the first hints that your
pet has heart disease. There are multiple possible causes of a heart
murmur, but the exact diagnosis will require further tests. Once the
diagnosis and severity of your pet’s heart problem is determined, it
can be discussed whether immediate treatment is necessary and how
this heart disease will affect your pet in the future.
What can cause a murmur?
Murmurs are created by turbulent blood flow. Normally the blood in the heart flows undisturbed and
smoothly (laminar flow). However, if there is a narrowing or the valves do not close properly blood will
flow rapidly (turbulence). This turbulent blood flow is what your veterinary surgeon will hear on
auscultation. The murmur can be rather quiet or very loud. Sometimes you can even feel it on your pet’s
chest. The intensity of the murmur does not necessarily tell us how bad the heart disease is, but it is an
important clinical finding and helps your veterinary surgeon to monitor your pet long-term and also to
communicate with other vets.
In order to better explain what can cause a murmur we will start with a brief description of the heart.
The heart is a muscular organ located in the chest that functions as a mechanical pump, propelling
blood through the body’s circulatory system. The heart is actually divided into two sides; a right side and
a left side. Each side has an upper chamber (atrium) and a lower chamber (ventricle).
Oxygen-poor blood from the body enters the heart at the right atrium, which contracts and forces blood
into the right ventricle. The right ventricle pumps this blood through a big vessel to the lungs, where it is
replenished with oxygen. The blood then returns to the heart, this time entering the left atrium. From here
the blood is directed into the left ventricle, which contracts and pumps blood into the aorta (vessel),
delivering oxygen-rich blood to the body.
Each side of the heart has a one-way valve located between the atrium and ventricle and another
valve between the ventricle and big vessels. The mitral valve separates the atrium and ventricle on the
left side, whereas the tricuspid valve separates these chambers on the right side. The aortic valve
separates the left ventricle from the aorta and the pulmonic valve separates the right ventricle from the
main pulmonary artery.
All these valves function as one-way valves with a forward flow direction. Failure to properly open or
close will disturb laminar blood flow and result in a murmur. Abnormal connections between vessels or
“holes” in the heart abnormally connecting heart chambers will also cause heart murmurs. Other reasons
for murmurs include, narrowing within chambers and blood vessels, fever, and anaemia.
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My pet has an innocent or “benign” murmur – do I have to be worried?
Innocent murmurs are often found in puppies (“puppy murmurs”) and cats of any age. In puppies they
normally disappear by the age of 5-6 months. These murmurs are not usually related to heart disease.
Congenital murmur and acquired murmur – What does that mean?
If your pet has a congenital murmur it means that the murmur has been present from birth. Pets with
congenital murmurs are born with a heart defect. It is important to find out what kind of disease they are
born with early on as some congenital defects can be fixed.
An acquired heart murmur is a murmur that appears later in life. The most common reason is mitral valve
disease in dogs and hypertrophic cardiomyopathy in cats.
My pet has a murmur – what is the next step?
A murmur is just a clinical finding and does not tell us the final diagnosis. Even though certain conditions
are more common than others, without further tests (e.g. echocardiogram (heart scan), x-rays) we
cannot establish a diagnosis, the severity of disease or what this might mean for your pet in the future.
Knowing about the disease will help you and your veterinary surgeon to make an educated decision
about possibly necessary treatment.
How do I treat a murmur?
The murmur itself will not be treated, but the underlying condition will be if indicated. The decision for
treatment will be made based on diagnosis, severity of disease, and other circumstances.
Would you like to see one of our heart specialists?
If you would like to have your pet’s heart murmur further evaluated, please ask your veterinary
surgeon to contact the Pride Veterinary Centre Cardiology Service at [email protected]
or call 01332 548911.
More questions?
If you are unsure whether your pet needs a heart work-up with one of our cardiologists or you have
questions in regards to treatment options, please discuss this with your veterinary surgeon and advise
them that they can contact us at any time to discuss your pet.