CARDIAC
EVALUATION OF THE CANINE ATHLETE
A
healthy heart is essential to successful performance for
any athlete and this is certainly true of canine competitors.
Heart disease in dogs may be present since birth (congenital
conditions) or may be acquired later in life. Dogs can develop
abnormalities of the heart valves or heart muscle, as well
as structural deformities. Clinical signs of heart disease
in dogs include exercise intolerance, fatigue, shortness
of breath, fainting, discoloration of the gums, coughing
and restlessness, particularly at night. Upon physical examination,
a veterinarian may detect abnormalities such as a heart
murmur, an abnormal heart rhythm, or a rapid or slow heart
rate. If heart disease is suspected, a consultation with
a veterinary cardiologist is strongly recommended in order
to further define the extent of the problem. This is particularly
important with working dogs and those that are actively
involved in competition. A thorough cardiac evaluation is
also recommended for young dogs that are about to enter
into competition for the first time.
Cardiac
evaluation begins with a complete physical examination and
auscultation of the heart with a stethoscope. Further assessment
is performed using a series of specialized diagnostic tests.
These include thoracic radiographs (chest x-rays), an electrocardiogram
(ECG), and an ultrasound examination of the heart, referred
to as echocardiography. These tests provide
different pieces of information about the overall health
of a dog's heart.
Chest
x-rays provide direct information regarding the size of
the heart and the condition of the lungs. The larger vessels
entering and leaving the heart can also be evaluated. In
cases of heart failure, fluid accumulation can be detected.
When x-rays are repeated over a period of time, they can
help judge the effectiveness of treatment.
An
electrocardiogram is a test used to record the electrical
activity of the heart and to detect abnormal heart rhythms
called arrhythmias. The ECG can also provide information
regarding enlargement of specific chambers of the heart
and the position of the heart in the chest cavity.
Echocardiography
is a highly specialized, non-invasive test that allows the
veterinary cardiologist to "see" inside the heart using
a form of sonogram. An ultrasound probe is placed on the
chest and sound waves are used to assess heart structure,
chamber size, and heart valves. The ultrasound exam allows
for evaluation of functional abnormalities such as weak
heart muscle contractions or incompetent heart valves. A
specialized test called "color flow Doppler" provides greater
detail about the blood flow through the heart. This test
is discussed in more detail elsewhere in this issue (see
page 5).
When
these tests are performed on a canine athlete, they provide
complete information regarding the dog's heart. If no abnormalities
are detected, the dog is cleared of any limitations due
to cardiac disease. In cases where one or several tests
are abnormal, the veterinary cardiologist will interpret
the information and formulate a treatment plan.
