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PET HEALTH BULLETIN
Autumn 2012
1. Heart murmur
At a routine vaccination visit, your vet
mentions your dog or cat has a heart
murmur. What does it mean for your beloved
companion? In this issue of the news letter,
we explain what a heart murmur is, and
what steps you can take to manage your
pet’s heart condition.
What is a heart mur mur?
A heart murmur is an abnormal heart sound
that is heard through your vet’s stethoscope.
The sound is produced by abnormal blood
flow that is turbulent. In a normal heart,
blood flows smoothly just as water would
through a quiet river. But when there is
narrowing of the stream, the water like blood
in the heart produces sound that is much
louder due to disruption in the otherwise
smooth flow. Similarly, if there is impedance
to the flow of blood through the heart, we
hear the turbulence as a heart murmur.
to the rest of the body. If this valve
starts to leak, then we hear a heart
murmur. In fact, up to 58% of dogs
aged 9 and above have changes
to their mitral valve.
What does the “grade” of the heart
murmur mean?
Heart murmurs are graded on the
scale of 1 to 6 according to the
intensity and loudness of the
murmur.
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What are the different types of murmurs?
There are generally two type of heart
murmur; congenital and acquired. A
congenital murmur is one that is present
from birth and is due to heart defects. These
could be due to a defect between the walls
of the heart (Atrial and septal defects) ,
narrowing of certain major vessels of the
heart (pulmonic and aortic stenosis) or
because a closing between two vessels has
failed to occur ( Patent Ductus Arteriosis). It
is not uncommon for young puppies or
kittens before 16 weeks to have a murmur.
Murmurs that resolve with age are generally
harmless.
The latter, an acquired murmur, is one that
your pet develops later in life and is usually
due to heart or valvular disease. The most
common acquired murmur is caused by a
defect in the mitral valve. It is a valve that
sits on the left side of the heart. It opens and
closes as the heart contracts to pump blood
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Grade 1 - Soft murmur
that are very soft and is
only audible via a
stethoscope in quiet
surroundings.
Grade 2 – Soft murmur
but easily heard by the
stethoscope one side of
the heart
Grade 3 - Intermediate
intensity heard by the
stethoscope over both
sides of the heart
Grade 4 – Loud murmur
heard by a stethoscope
but no thrill
Grade 5 – Loud murmur
heard by a stethoscope
and a palpable thrill
(meaning you can feel the
murmur by placing your
hands over the heart)
Grade 6 – Very loud, you
can hear the murmur
without the stethoscope
Though grading of the heart
murmur signifies the increasing
intensity of the turbulent flow of the
blood, it does not relate to
prognosis (outcome) of the heart
condition.
What are the treatments for a heart
murmur?
Treatment only commences if your pet’s
heart murmur progresses into heart failure.
This is when your pet starts exhibiting signs
such as collapse, coughing, difficulty
breathing, exercise intolerance and lethargy.
It is important to visit your veterinarian, at
least once a year, to monitor the progress of
the heart murmur and to report any
symptoms if they occur.
Your veterinarian might propose to do
diagnostic imaging to work out the cause
and severity of the heart murmur. An x ray
will help evaluate the size of your pet’s heart
and identify signs of heart failure (such as
fluid in the lungs). An echocardiogram
allows us to assess the structure of the heart
which is not visible on x rays. It uses sound
waves to create images of the heart in
motion, similar to an ultrasound. Certain
measurements are taken and these help us
to tailor the best treatment protocol. The
measurements can also be used to assess
response to treatment at a subsequent
echocardiogram. Recently, there is also a
blood test available to determine if your pet’s
heart has gone into failure. It measures a
specific enzyme released by a failing heart.
To date, there has been no evidence to
suggest treating a heart murmur prior to
development of clinical signs improves the
outcome of the condition. Therefore,
treatment for a heart murmur commences
only when you notice signs of heart failure.
The heart murmur itself is untreatable and is
irreversible. However, the heart failure can
be successfully managed with drugs.
Regular blood tests and check ups are
needed since medication changes after
some time. This will help improve and
maintain a quality of life your pet will enjoy
with medication.
What else can I do for my pet?
In addition, to regular check up to monitor
your pet’s heart. There are other steps you
can take to help your pet’s heart.
Maintaining a good weight limits
the strain that is placed on the
heart. Avoid food that is high in
salt content such as processed
food, chips, cheese and some
canned food. Vitamin B
supplementation can also be
helpful since it replaces the loss as
a consequence of heart failure.
Supplementing their diet with
Omega 3 fatty acid can also be
beneficial. Lastly, avoid heat
stress.
Many pets with heart murmur
continue to lead normal lives.
Those that develop heart failure
can be successfully managed to
give them optimal quality of life.
2. Clinic News
Dr Michael Banyard will be taking
a 6 month leave of absence from
April. He will be sorely missed by
the staff at the Animal Medical
Centre, as a colleague, a mentor
and a friend. We hope he will
return to do further work with us
and we wish him the very best
during his extended break.
Rebecca Taylor, one of our lovely
nurses, will also be leaving to
pursue a career as a human
nurse. Dr Amanda Craig, a well
known Canberra vet with a special
interest in dermatology and
pharmacology will be joining us in
mid April. Laura Palmer, a bright
young vet nurse, has already
started with us and we warmly
welcome them both. We now have
a new kennel and x ray facilities.
We are continuing to improve our
facilities to serve you better.