Veterinarians use a stethoscope to listen to the heart. You can listen to
your dog’s heart by placing your ear against his chest. The
normal heartbeat is divided into two sounds. The first is a lub,followed by a
slight pause and then a dub. Put together, the sound is lub-dub, lub-dub . . .
in a steady, evenly spaced rhythm.
The heartbeat should be strong, steady, and regular. A slight alteration in
rhythm as the dog breathes in and out is normal. An exceedingly fast pulse can
indicate anxiety, fever, anemia, blood loss, dehydration, shock, infection,
heat stroke, or heart (and lung)
disease. A slow pulse can indicate heart disease, pressure on the
brain, or an advanced morbid condition causing collapse of the circulation.
Heartworm disease, so named
because the adult worms live in the right side of
the heart, continues to be a major problem for many species of animals.
Heartworms are spread by mosquitoes, and thus are found throughout the world.
In the United States the prevalence is highest along the southeastern Atlantic
and Gulf Coasts, but heartworm has been found in all 50 states. The disease is
less prevalent at higher elevations.
The highest infection rates (up to 45 percent) in dogs
An erratic, irregular or disordered pulse indicates a cardiac arrhythmia.
Many arrhythmias are associated with a sudden drop in blood pressure as the
arrhythmia begins. The corresponding decrease in blood flow to the muscles and
brain is accompanied by sudden weakness or collapse, often giving the
impression of a fainting spell.
When the heart sounds can be heard all over the chest, the heart is probably
Heart murmurs are common.
Murmurs are caused by turbulence in the flow of blood through the heart.
Serious murmurs are caused by heart disease or anatomical defects.. Anemia can
cause a heart murmur.
Not all murmurs are serious. Some are said to be innocent; that is, there is
no disease, just a normal degree of turbulence. To determine whether a murmur
is serious or innocent, your veterinarian may request diagnostic studies such
as a chest X-ray, an electrocardiogram (ECG or EKG), and an echocardiogram.
Thrills are caused by turbulence of such a degree that you can feel a
buzzing or vibration over the chest. This suggests an obstruction to the flow
of blood-for example, a constricted valve or a hole in the wall between two
chambers of the heart. A thrill indicates a serious heart condition.
The pulse, a transmitted heartbeat, is easily detected by feeling the
femoral artery, located in the groin. With your dog standing, or preferably
lying on his back, feel along the inside of the thigh where the leg joins the
body. Press with your fingers until you locate the pulse.
You can also feel a dog’s pulse by pressing against the rib cage over his
heart. Feel the heartbeat just below and behind the elbow joint. If the heart
is enlarged or diseased, you may be able to detect a buzzing or vibration over
the chest wall.
The pulse rate is determined by counting the number of beats per minute.
Most adult dogs at rest maintain a rate of 60 to 160 beats per minute. In large
dogs the rate is somewhat slower and in toy dogs it’s somewhat faster. In young
puppies the heart rate is about 220 beats per minute.