The only way to tell if a murmur
is benign versus pathologic is to
perform echocardiography (
sometimes also called a sonogram, or
Echocardiography is best
performed by a veterinary
cardiologist. (Yes, there are veter-
inarians that specialize in cat and
dog tickers only.) These cardiol-
ogists know exactly how thick or
how thin the walls of each heart
chamber are supposed to be, how
fast the blood should be flow-
ing as it travels out of the aorta
and pulmonary artery, and how
strongly the heart is supposed
to be contracting. By viewing the
heart using ultrasound and taking
a variety of measurements, the
cardiologist can determine if heart
disease is present.
The most commonly diag-
nosed heart disease in cats
is a condition called hypertrophic
cardiomyopathy (HCM). In cats
suffering from HCM, the walls of
the heart become progressively
thicker, with one particular cham-
ber, the left ventricle, usually
becoming the most affected.
Think of the left ventricle as
a coffee mug. Now imagine the
walls of the mug becoming thicker
and thicker, growing inward. The
mug would hold less and less
In HCM, the ventricle holds
less and less blood. If the ventricle can now hold only half as
much blood, the heart will try to
compensate by pumping twice as
hard to achieve the same effect.
Eventually, the muscle starts to
give out, and congestive heart failure may develop.
Cats diagnosed with HCM
The most serious com-
plication of HCM is a
condition called aortic thrombo-
embolism (ATE). In ATE, a blood
clot develops in the left atrium.
A piece of the blood clot breaks
free, travels down the aorta, and
gets lodged at the very end, where
the aorta branches to supply the
legs with blood. Cats become
acutely paralyzed in the rear legs
as a result.
This is a truly devastating complication that carries a very grave
prognosis. Sadly, as a feline practitioner, I have the terrible misfortune of seeing two or three cases
of ATE a year, and every case ends
HCM can strike any breed
of cat. However, Maine
Coons and Ragdolls are predis-
posed to the disorder. Fortunately,
the reason for their susceptibility
was discovered several years ago:
a mutation in the gene that codes
for a specific protein in the heart.
A genetic test has been devel-
oped to screen cats for the dis-
order. The test requires either a
cheek swab or a blood sample.
Responsible cat breeders can now
test their cats for this mutation
and use selective breeding tech-
niques to hopefully eliminate the
gene from the population.
Kittens will sometimes
have a heart murmur
that disappears as they mature.
A persistent murmur in a kitten,
however, should be investigated,
as congenital heart diseases occasionally do occur. The sooner they
are diagnosed and treated, the
better the prognosis.
Dr. Arnold Plotnick is the founder
of Manhattan Cat Specialists,
a feline-exclusive veterinary
practice on Manhattan’s upper
west side. He is also an author
of The Original CAT FANCY Cat Bible. Dr.
Plotnick is the former Ask the Veterinarian
columnist for CAT FANCY magazine and is
a frequent contributor to feline publications
and websites, including his own blog, Cat
Man Do. He lives in New York City with his
A cat’s normal heart
rate is 160 to 240 —
much faster than a
DID YOU KNOW?
Coronary artery disease is the most common cause of death in humans in
the United States. Fortunately, cats don’t get coronary artery disease. Nature,
however, doesn’t play favorites when it comes to other heart diseases, and
cats are indeed susceptible to disorders of this vital organ.