At the Animal Clinic at Thorndale, we are very fortunate to have a number of veterinary specialty practices close by. When advance diagnostics screening is needed for your cat, out doctors will set up a referral with the right specialist for the right problem. Ultrasounds, echocardiograms, CT scans and MRIs are all just a short drive away from our Downingtown, PA location.
If your cat has been scheduled for an ultrasound examination, understanding the process will help you and your cat be more comfortable. Ultrasound is a high tech way of imaging internal organs without x-ray radiation. Instead, ultrasound uses the reflection of high-frequency sound waves to evaluate the size, shape and position of organs and tissues.
Ultrasound does not replace traditional x-ray examination of the organs. Instead, it complements x-rays and can provide information which the x-ray does not, and vice versa. It does offer several advantages over x-rays. It is safer for the operator than x-rays because sound waves do not represent a dangerous energy source. Also, organs which may not be visible at all on x-rays, such as lymph nodes and the pancreas, can be seen on ultrasound. Also, “real time” or moving images may be produced.
Air and bone are the enemies of ultrasound waves. Since the lungs are air-filled, they cannot be studied during an ultrasound examination. The exception is a mass located within the lungs. Bones cannot be studied because they reflect the sound waves back to the ultrasound machine without producing an image. Because of the problems with imaging bone, the brain and spinal cord are not seen with an ultrasound study.
Prior to the study, the fur is clipped over the area of interest. For an abdominal ultrasound, your cats entire underside may be clipped. Next, a water-based gel or alcohol is applied to the skin to improve contact between the transducer and skin. The transducer is held in the operator’s hand and moved over the skin. When sound waves are emitted from the transducer, they are reflected back to the ultrasound machine. The pattern of the reflected sound waves creates an image that is viewed on a screen.
In general, ultrasound is used to examine the heart or to study organs within the abdomen, such as the liver, kidneys, spleen, or bladder. Cardiac ultrasound, also called an echocardiogram or an “echo,” can measure the thickness of the heart walls and the size of the individual heart chambers. The heart valves can be examined for normal motion and any thickened areas. Motion can be detected so that an assessment can be made of the ability of the heart of move blood.
Some specific diseases can be diagnosed because they have a specific ultrasound appearance. However, other diseases cause ultrasound findings that are not unique. Even when non-specific findings are detected, ultrasound is still very helpful in detecting abnormal areas within a particular organ. Determination of an abnormality allows the veterinarian to obtain a fine-needle aspirate or biopsy of the precise site. The needle aspirate or biopsy produces a preparation of cells that are smeared on a slide. It usually does not require sedation because it is no more painful than a blood sample collection. It is a good screening tool but, in some cases, may not provide a diagnosis. In these situations, it may be necessary to obtain a tissue biopsy. A tissue biopsy recovers an actual piece of tissue for the pathologist to examine under the microscope for more information. In many cases, the ultimate diagnosis is made by the pathologist.
No special preparation is needed if the heart is to be studied. If organs in the abdomen are to be studied, your cat should be withheld from food for 18 hours. The urinary bladder is best visualized if it is full of urine. Therefore, do not let your cat urinate within 3-6 hours of the study, if possible.
If your cat is cooperative, no anesthesia or sedation is needed to ultrasound the heart or the abdomen. However, if biopsies are to be taken, a short-acting anesthetic may be needed to prevent complications.
Since an ultrasound study is performed in real time, the results of what is seen are known immediately. In some cases, the ultrasound images are sent to a veterinary radiologist for further consultation. If this happens, the final report may not be available for a few days.