Heart Murmurs in Dogs and
Cats
What is a heart murmur?
When your veterinarian listens to your pet’s heart during their
physical exam, the heart sounds are very similar to human heart sounds,
described as “lub dub...lub dub...lub dub”.
A heart murmur is an abnormal heart sound that is caused by turbulent
blood flow. If your pet has a heart
murmur, rather than these regular sounds, the heart beats may sound like “lub
swoosh...lub swoosh...lub swoosh”. The
swooshing sound is caused by a disruption in smooth and regular blood flow
through the heart.
What kinds of disease can cause a heart murmur?
A heart murmur is a clinical sign of heart disease, but it is not
specific for the cause or the severity of your pet’s underlying heart
disease.
In cats, heart murmurs are often caused by
abnormal thickening of the heart walls, causing the heart walls to become stiff
and rigid. In turn, this reduces the
amount of filling and pumping the heart can do.
The most common cat breeds affected are Maine Coon and Ragdoll.
In
small dogs, heart murmurs are often caused by degeneration of the valves that
keep blood flowing in a forward direction.
Specifically, the mitral valve, which forms a tight seal from the left
atrium to the left ventricle, and can degenerate over time and allow blood to leak
backwards into the atrium every time the heart pumps. Other valves can also become degenerative
over time, but the mitral valve is the most common. The most common breeds affected are Cavalier
King Charles Spaniels, Miniature Poodles, Cocker Spaniels, Miniature
Schnauzers, and Dachshunds.
In
puppies and kittens, a murmur detected on physical exam may be a sign of a
congenital abnormality that may require early and aggressive treatment, or may
go away within a few weeks of birth.
Fortunately, these murmurs are rare.
How do I know if my pet has a heart murmur?
You cannot tell your pet has a heart murmur just by looking at
them. Heart murmurs are detected on
physical exam when your veterinarian listens to your pet’s heart sounds with a
stethoscope. If a heart murmur is
detected for the first time during an exam, your veterinarian may recommend to
re-check the murmur in a few weeks to see if it is still present or has
changed. Murmurs are graded on a scale
from 1-6 and allow veterinarians to monitor for progression of the murmur over
time. Other signs of heart disease that
you can watch for at home are coughing, exercise intolerance, lethargy, or increased
respiratory (breathing) rate.
My pet has just been diagnosed with a heart murmur, what do I do
next?
If your pet has just been diagnosed with a heart murmur, there is
no need to panic. Many dogs and cats
have murmurs that do not progress to heart failure; they live a long full life
that does not require treatment of their heart disease. However, additional diagnostic tests may be
necessary to determine the specific type of heart disease and how advanced it
may be. These tests help you and your
veterinarian to determine if treatment is necessary.
Chest x-rays may be recommended by your
veterinarian to monitor for evidence of heart enlargement.
An
echocardiogram is an ultrasound exam of the heart; this test is useful to
determine the exact cause of your pet’s heart disease and also determine how
well your pet’s heart is functioning.
Other
tests such as an ECG (electrocardiogram) to evaluate the heart’s electrical
activity, blood pressure, or blood tests may also be recommended.
In
some cases, referral to a veterinary cardiologist may be recommended.
Here is a radiograph of the heart and lungs
How do you treat a heart murmur?
There is no specific treatment for a heart murmur, but depending
on the specific case, medications may be indicated. Some heart disease medications work to decrease
the work load on the heart by lowering blood pressure or decreasing blood
volume. Other medications are used to
improve amount of blood the heart pumps out by strengthening the heart muscle
contractions or slowing the heart rate to make the heart a more effective
pump. If your pet is diagnosed with a
heart murmur, discuss the appropriate treatment options that are available to
you and your pet.
Here Dr. Helgen is pictured performing an echocardiogram
(ultrasound of the heart) to evaluate a patient with a heart murmur.
An annual physical exam with your veterinarian is vital to detect
heart murmurs, which are often the earliest and most subtle signs of underlying
heart disease. If your pet has a newly
discovered heart murmur, talk to your veterinarian about what diagnostic tests
are available, treatment options, and what you can be watching for at
home.
For additional information, please
visit these sites:
Dr. Colleen Helgen Capitol Illini Veterinary Services Springfield, IL January 2014
