This article is on the use of ultrasound in veterinary medicine. This diagnostic tool can be very useful in the evaluation of organs inside the body when other tests or mediums cannot fully diagnose a problem. It is usually used as a complementary diagnostic tool after other tests have been run to give the doctor more information in order to better treat an illness. I will discuss when an ultrasound should be performed, what can be evaluated with a scan, and its limitations as a diagnostic exam.
Many parts of the body can be scanned with an ultrasound machine, however, in our practice most of the time the organs of the abdomen are evaluated to help with a diagnosis. Abdominal organs include the liver, spleen, stomach, intestines, kidneys, urinary bladder, gall bladder, and others. Major vessels and lymph nodes can be seen as well. The abdominal ultrasound can be used in compliment to x-ray views of the abdomen to fully diagnose an illness. Problems like chronic illness of the gastrointestinal tract, hepatitis (of which there can be several forms), kidney disease, urinary bladder disease, and disease of the spleen can be found with or evaluated because of the unique appearance of the organs on the ultrasound and specific locations of disease on that organ may be apparent when scanning. The size and function of some organs may be measured on the ultrasound as well, this cannot be done on an x-ray. If there is a suspicion of growths or masses in the belly, the ultrasonographer may be able to locate them and be able to measure the size of those objects and determine if surgery is possible, a fine needle aspirate to be done, or a biopsy to be performed.
The second most common area that is scanned by ultrasound is the chest, and more specifically, the heart. Heart disease is best evaluated by the echocardiogram, not an x-ray because the heart can be directly viewed to evaluate the size, function of the muscle, and appearance. X-rays of the chest can detect the presence of heart enlargement, and problems in the lungs surrounding the heart but they are limited in the diagnostic value of actual heart disease. These two mediums are used complementary to each other because the lungs and heart can be evaluated fully when they are performed together. Once these diagnostics are performed, the best treatment for the disease can be planned and started soon after. Also, echocardiograms can be used as a follow-up on heart disease to evaluate the treatments and the effect of the treatment on that patient.
There are other tests that can be aided by ultrasound when necessary. Fine needle aspirates (FNA) for cell cytology of certain organs can be done when the ultrasonographer locates the area needed to be aspirated with the machine. The needle can be seen on the screen and a sample be taken for cytology. Also, a needle biopsy can be taken of the liver as well. The most common sampling in our practice that is aided by the ultrasound machine is urine collection. When it is necessary, a needle is used to collect urine from the bladder in order to be tested by urinalysis or for the growth of bacteria in that sample. Scanning the bladder at the same time also allows for the evaluation of the bladder walls, and the appearance of urine in the bladder, and can rule out the presence of urinary stones.
There are limitations to an ultrasound! There are no perfect diagnostic tests of any kind. Detection of masses or growths can be performed but it cannot tell you specifically what they are, that is why an FNA or biopsies are performed. Air is not a friend to the ultrasound waves, and it cannot be diagnostic when diseases of the lungs need to evaluate. An abdomen can appear normal on ultrasound, but the patient may have severe changes in blood work indicating disease somewhere inside. In short, an ultrasound is not indicated for all diseases.
At St. Francis Hospital for Animals, we can perform certain ultrasounds on our own, or depending on the situation, have them done by more experienced colleagues. Usually, when we need a full evaluation by an experienced ultrasonographer, we schedule one with Dr. Amy Haase. Dr. Haase is a traveling ultrasonographer who performs abdominal, heart, and cervical (neck) ultrasounds, and can perform guided FNAs and biopsies if needed. She has a great bedside manner, and clients are welcome to be present at the time of the ultrasound. We are lucky to have her as a colleague and be available to us at St. Francis. If a more urgent diagnosis is needed, we may need to refer to an outside veterinary specialist for the ultrasound evaluation. My comfort level with ultrasounds is scanning the bladder, searching for fluid in the abdomen, and looking for masses in the abdomen. As I gain more experience, I will perform more ultrasounds, allowing for more immediate diagnoses, if needed. The determination of who performs them is on a case-by-case basis, and what is practical for the client and the patient.
In summary, the use of ultrasound in our practice can be a very useful tool to help in detecting, evaluating, and diagnosing disease. It may not always be needed, but may be necessary when a primary diagnostic test does not find the answer we need to best treat a patient. If you have any questions, please give us a call, or ask on your next visit.
Dr. Jaime Kozelka
St. Francis Hospital for Animals