What is an “ultrasound”?
An ultrasound test is a radiology technique, which uses high-frequency sound waves to produce images of the organs and structures of the body. These sound waves are transmitted with a device called a transducer to the area of interest. The transducer is placed directly on top of the skin with some gel applied. The technique measures different amounts of resistance the body parts offer to the sound waves, and then uses the data to produce a “picture” of the structures. In effect, the “echoes” return to the transducer and are transmitted electrically onto a viewing monitor. Ultrasound is often used to obtain an image of the developing fetus in pregnant women. Ultrasound is often considered a safer alternative to x-rays or other diagnostic methods because ultrasound is noninvasive, involves no radiation, and avoids the possible hazards—such as bleeding, infection, or reactions to chemicals—of other diagnostic methods.

What is an echocardiogram?
The echocardiogram is an ultrasound of the heart. Using standard ultrasound techniques (see above), two-dimensional slices of the heart can be imaged. The standard echocardiogram is also known as a transthoracic echocardiogram, or TTE. In this case, the echocardiography transducer (or probe) is placed on the chest wall of the subject, and images are taken through the chest wall. This is a non-invasive, highly accurate and quick assessment of the overall health of the heart. A cardiologist can assess a patient’s heart valves and degree of heart muscle contraction (an indicator of the ejection fraction). The echo is a popular test which keeps improving. In addition to creating two-dimensional pictures of the cardiovascular system, the echocardiogram can also produce accurate assessment of the direction of blood flow and the velocity of blood and cardiac tissue using Doppler ultrasound. This allows assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), and calculation of the cardiac output as well as the ejection fraction.

What is an ECG?
The electrocardiogram (ECG or EKG, the K is from “kardio” in German) is a noninvasive test that is used to reveal underlying heart conditions by measuring the electrical activity of the heart. Information about many heart conditions can be learned by looking for characteristic patterns on the ECG by positioning leads (electrical sensing devices) on the body in standardized locations. ECG leads are attached to the body while the pet lies with the right side down on the floor or a table. Leads are attached to each extremity (4 total) and occasionally to 6 pre-defined positions on the chest and back.

What is measured or can be detected on the ECG of my pet?
The underlying rate and rhythm of the heart can be measured, and this is the most important role of the ECG. Other less important and less diagnostic functions include the orientation of the heart (how it is placed) in the chest cavity, evidence of increased thickness (hypertrophy) of the heart muscle, evidence of damage to the various parts of the heart muscle, evidence of acutely impaired blood flow to the heart muscle (very rare in most animals), and patterns of abnormal electric activity that may predispose the patient to abnormal cardiac rhythm disturbances.

What are the limitations of the ECG of my pet?
Many abnormal patterns on an ECG may be non-specific, meaning that they may be observed with a variety of different conditions. They may even be a normal variant and not reflect any abnormality at all. These conditions can often be sorted out with a detailed examination and other cardiac tests (e.g., echocardiogram, blood pressure and others). In other instances, the ECG may be entirely normal despite the presence of an underlying cardiac condition that normally would be reflected in the ECG. The reasons for this are largely unknown, but it is important to remember that a normal ECG does not necessarily preclude the possibility of underlying heart disease. Furthermore, a patient with heart symptoms can frequently require additional evaluation and testing.

What is a Holter monitor?
A Holter monitor is a type of portable heart monitor. The Holter monitor is a small portable electrocardiogram (ECG). The device is worn in a pouch around the shoulder, fastened onto a harness and taped. Most dogs, large and small, do quite well with this device for 24 hrs. It keeps a record of the heart rhythm, typically over a 24-hour period, while the patient owner keeps a diary recording the activities and any symptoms their pet may feel or show. The ECG recording is then correlated with the pet’s record of their activities and symptoms. The Holter monitor is useful for identifying disturbances which are sporadic and which are not readily identified with the usual resting electrocardiogram test.

How do patients prepare for an echocardiogram?
Preparation for an echocardiogram (echo) is minimal: the patient should take all medications that are normally administered, and food and water can be given. If it is known that the pet is particularly fractious, a mild sedative may have to be given and the owner may refrain from giving food 12 hrs prior to the examination. The pet will be firmly but lovingly restrained on a special table, in right lateral recumbency. Shaving of the area to be examined (close to the right elbow on the right chest) is not usually necessary, but the pet will be sprayed liberally with alcohol to get to the skin. A warmed gel will then be applied to the area and the ultrasound probe will be placed. This can be scary but does not hurt. For increased comfort to the pet and better communication, the owners are usually present during the echocardiogram.

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What is hypertrophic cardiomyopathy?
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What is dilated cardiomyopathy?
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What is mitral valve insufficiency?
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What is tracheal collapse?
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What is pulmonic stenosis (PS)?
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What is subaortic stenosis (SAS)?
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