Blood flows into the
right side of the heart. The right
ventricle then pumps the blood into the lungs where it picks up oxygen. The blood then flows into the left side of
the heart where it is pumped back out into the body. As the blood flows into the different
chambers of the heart, valves close behind it to ensure the blood continues to
flow in the correct direction. The sound
that is heard when listening to the heart is the sound of the valves slamming
shut.
If the valves do not
operate properly, some of the blood will be pushed backwards. If the valve fails that closes behind the
blood flowing into the right side of the heart, then blood will back up into
the liver and abdomen and cause “ascites”.
If the valve fails that closes behind the blood flowing into the left
side of the heart, then blood will back up into the lungs.
Congenital heart
disease can occur in any size dog.
Typically, the heart valves do not form properly, leading to failure to
function properly. The valves don’t seal
the openings; and therefore, you can hear the blood leaking through the valve
making a ‘whooshing’ sound. This sound
is referred to as a murmur. Diagnoses of
a heart murmur is made by using a stethoscope to listen to the heart. Many dogs can live for years with a murmur
without developing CHF.
Congestive heart failure
(CHF) is a very common disease in dogs.
CHF can occur in both large and small breed dogs although the underlying
causes vary significantly. In small
breed dogs, the most common cause is chronic dental disease. The bacteria in the mouth set up residence on
the heart valves. Eventually, the valve
begins to thicken and function improperly, leading to CHF. In large breed dogs, the most common
underlying cause is due to the heart being over worked. This leads to a thickening of the heart wall
and the failure of the heart to properly pump the blood. Additionally, severe heartworm infestations
can lead to CHF in any size dog.
Symptoms of CHF depend
on which side of the heart is affected.
Right sided CHF will lead to ascites.
If the blood is being backed up into the abdomen, then the belly will
start to fill with fluid and become distended.
If the blood is being backed up into the liver, then you can start to
see signs of liver failure (jaundice, vomiting, loss of appetite, etc.).
Left sided CHF will
lead to blood being backed up into the lungs.
The dog will usually wheeze or cough.
The cough is often productive, meaning that they cough up fluid.
With both types of CHF,
the dog will have a decrease in energy and possibly a loss of appetite.
Treatment of CHF also
depends on the underlying cause. It can
include: medication to increase heart muscle contractions, diuretics to draw
the extra fluid out of the lungs, liver, or abdomen, and a special diet.
