Some cats diagnosed with hypertrophic cardiomyopathy are not showing
any signs of illness at the time of their diagnosis. When signs do
appear, they can show up quite suddenly and can be quite serious.
Congestive heart failure occurs frequently in cats with
hypertrophic cardiomyopathy. Typically, the left side of the heart is
more involved than the right, so the signs of hypertrophic
cardiomyopathy are those of left-sided congestive heart failure.
Signs of left-sided congestive heart failure are:
- Difficulty breathing
- Increased respiratory rate
- Increased respiratory effort
- Increased heart rate
- Weakness
- Lethargy
- Lack of appetite
- Fainting spells (usually caused by an irregular heart rate known as an arrhythmia)
- Cyanosis (a purple or blue color in the gums due to a lack of oxygen) in extreme cases
Possible Additional Clinical Signs
Cats with hypertrophic cardiomyopathy may also develop an aortic
thromboembolism. This occurs when a blood clot breaks loose from the
heart and becomes lodged at the end of the aorta causing the blood flow
to the hind legs to stop.
Cats suffering from aortic thromboembolism will suddenly become
paralyzed on their hind legs or have a difficult time walking and will
be quite painful. The hind legs may become cold to the touch because of
the lack of circulation and you may not be able to find a pulse in the
hind legs.
In some cases, young apparently healthy cats may develop signs of
hypertrophic cardiomyopathy while undergoing a routine surgical
procedure, such as a spay or neuter. Signs may also appear shortly after
the procedure is finished. It is likely in these cases that the heart
condition existed prior to the procedure but was asymptomatic (not
causing signs of illness) and so not diagnosed.
Unfortunately, sudden death also sometimes occurs in cats with hypertrophic cardiomyopathy.
Diagnosing Cats with Hypertrophic Cardiomyopathy
On physical examination, cats with hypertrophic cardiomyopathy
may or may not have a heart murmur. Arrhythmias (irregular heart beats)
may be present also but an electrocardiogram (EKG or ECG) is needed to
accurately diagnose any arrhythmia.
The most valuable diagnostic test for hypertrophic cardiomyopathy
is an echocardiogram. An echocardiogram is an ultrasonographic
examination of the heart. It allows direct visualization of the
thickness of the heart muscle and the diameter of the chambers of the
heart as well as allowing the veterinarian to evaluate the function of
the various structures of the heart.
In most cases, other laboratory tests will also be necessary and
may include blood testing to rule out hyperthyroidism and other causes
of illness in addition to measurement of the blood pressure.
Please note: this article has been provided for informational
purposes only. If your pet is showing any signs of illness, please
consult a veterinarian as quickly as possible.