TALK TO THE
VETS
by
dtlavets
Cardiac Disease
Although dogs and cats do not have to worry about “good
cholesterol” and “bad cholesterol”, they can still be plagued
with heart disease. Genetic predisposition is probably the
most influential factor in the development of cardiac disease
in our pets. Some breeds like Poodles, Cavalier King Charles
Spaniels and Chihuahuas are more likely to develop this problem. While most heart disease does not appear until later in
life, some puppies and kittens can be born with cardiac abnormalities. Some of these abnormalities can be surgically corrected while others are fatal.
Here we will describe the more common forms of heart disease in the adult and older pet population and give you some
tips for monitoring your pet at home.
Dogs will typically demonstrate their cardiac disease in the
walls and valves of the heart muscle. Dilated cardiomyopathy
(DCM) is a disease which results in thin, flabby heart walls and
weakened cardiac contractions. When the contractions are
weak, the heart is not emptying itself of blood as it should. This
allows blood to “back up” and often causes the heart valves
to leak and then thicken in response. Pressure builds and the
heart starts to enlarge. The most common result of DCM and
valve disease is congestive heart failure, an accumulation of
fluid in the lung tissue. Once this happens the dog can no longer oxygenate properly, breathing becomes more difficult and
eventually impossible.
Hypertrophic cardiomyopathy (HCM) is the most common
type of feline heart disease. Cats with HCM will also demonstrate their cardiac disease in the walls of the heart muscle.
But unlike dogs who develop flabby walls, HCM creates thickened and stiff walls. Often the size of the heart wall increases
inward rather than outward so that the space inside the chamber decreases and blood has no room to be present inside the
chamber. Once again the blood “backs up” and fluid begins
to accumulate in the lungs. Blood that is filling abnormally in
the heart is prone to clot formation. These clots can break
off and travel to other areas of the body which, once lodged,
can be very painful. While genetic predisposition can explain
some cases of feline cardiac disease, heart disease can also
occur secondary to hyperthyroidism, high blood pressure or
congenital narrowing of the aorta (the major vessel that delivers oxygenated blood from the heart to the body).
X-rays and ultrasound are the best tools to diagnose heart disease and its severity. Once heart disease is diagnosed, these
tests should be routinely performed every 6-12 months.
Normal x-ray. On x-rays, air is black, while thick dense tissues
(like bone or heart) are white. Normal lung tissue should be airfilled and therefore very dark on an x-ray. This is an x-ray of a
normal-sized dog heart.
This is an x-ray of a dog with DCM. He has a severely enla