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Client Library Article
CANINE DILATED CARDIOMYOPATHY
| About Canine Heart
Disease |
| Dilated cardiomyopathy (DCM) is a very common
form of cardiac (heart) disease in dogs. In DCM, the heart muscle
becomes thin and floppy and is unable to contact properly leading to a
smaller volume of blood being pumped out the heart to the rest of the body.
Initially, the body is able to compensate for the decreased cardiac output
of blood by increasing the heart rate and retaining sodium to increase blood
volume. But eventually, as the myopathy (heart muscle disease)
progresses, the heart itself enlarges and the heart valves start to leak.
When this occurs, a heart murmur is heard with each heart contraction. DCM
is a progressive disease which worsens over time eventually throwing the dog
into congestive heart failure. Almost 90% of DCM occurs in Doberman Pinchers, Boxers, Giant
breeds including Great Danes, Borzois, and Wolf Hounds, and Cocker
Spaniels. |
| Symptoms of Heart
Disease |
- Soft non-productive cough- usually worse at night
- Exercise intolerance & shortness of breath
- Weight gain or loss
- In heart failure- labored breathing / wheezing
- Swelling of abdomen
- Weakness & eventual collapse
- Shock with purple or blue tinged gums
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| Diagnosis |
- On physical exam, the veterinarian will
carefully listen to the heart with a stethoscope to listen for heart
murmurs, muffled heart sounds, and irregular beats and rhythms. The
pulses are felt at the same time to identify pulse deficits- when a heart
beat is heard but there is no associated pulse.
- Pulse strength and quality is assessed as well.
- In congestive heart failure, and a dog will have labored
breathing, a high heart rate, and weak pulses. If the dog has left
sided heart failure, fluid crackles can be heard in the lung fields
indicating pulmonary edema. With right sided heart failure, fluid builds
up in the space around the lungs which makes it difficult for the lungs to
expand with each breath. The build up of fluid is termed pleural
effusion. Many dogs present with both pleural effusion and pulmonary
edema indicating biventricular or left and right sided heart failure.
- Radiographs (X-rays) are used to evaluate
the heart shape and size. In DCM, often a very large heart is seen.
The lung fields are often clear unless the dog is in heart failure where
fluid densities can be seen in and around the lung fields.
- ECG or electrocardiogram traces out the
heart’s electrical activity and is used to assess rate, rhythm, and heart
enlargement based on the shape and size of different parts of the
electrical complex.
- A flat line ECG (often seen in
the movies) indicates no electrical activity in the heart which equals
death.
- Echocardiogram (echo) is the
technical name for an ultrasound of the heart.
- An "echo" is the ultimate diagnostic tool for diagnosing &
evaluating heart disease. Ultrasounds are used to
look at the actual function of the heart and to measure the size of the
heart chambers, thickness of the walls, valves, and major vessels.
Additionally, blood volume and direction of flow can be evaluated via
doppler probe- which
allows the cardiologist to measure cardiac output (blood volume pumped
through the heart) and evaluate the severity of murmurs. With an
echocardiogram, the cardiologist can accurately assess the degree of heart
disease, give a more accurate prognosis, and most importantly choose the
appropriate medication (s) for each animal. (see about echos in the
cardiology page)
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| Treatment |
| There is a wide variety of heart medications
available (most of which are used to treat disease in humans), and treatment
is based on the individual animal. Most dogs with DCM are
placed on digoxin- a drug used to slow heart rate, and increase the ability
of the heart muscle to contract normally. Beta blocking drugs are added to
further decrease heart rate and allow for a stronger contraction. Sometimes
ACE inhibitors such as enalapril are used. Lasix® or
furosemide is a common diuretic used to help decrease the buildup on fluid in and
around the lungs, and eliminate extra sodium in the urine. Many other drugs
can be used, most on a temporary basis, to improve cardiac function.
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Prognosis
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| Entirely dependent upon each individual but generally
guarded to poor prognosis for long term survival.
**With early diagnosis and proper therapy, a dog can do well for
some time with the disease. |
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