The survey ultrasound study is primarily used to assess soft tissue composition and in some cases function (echocardiogram) as well as guide you in biopsying "soft tissue" lesions. It has limited value in assessing bone-primarily restricted to the bone surface and it has no value in evaluating gas other than letting you know gas is present.
Before pathology can be discussed, the normal appearance of the liver, biliary system, and pancreas will be reviewed. Determination of liver size via US is not accurate and is best done on radiographs. Ultrasound is best performed with the animal in dorsal recumbency (on their back) and the area must be clipped free of hair.
While standard radiographic and ultrasound imaging techniques are common diagnostic tools in exotic animal medicine, the use of more advanced imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) currently appear to be underutilized for exotic patients.
Initially it is important to be able to identify radiographic signs of cardiac chamber enlargement. The left atrium on the lateral view when enlarged causes a change in shape of the dorsocadual aspect of the cardiac silhouette.
Radiology is like standing on the outside of the building; it allows you to see the size, shape and contour of the building; ultrasound allows you to look into each room in the building i.e. the liver room, the gallbladder room, the pancreas room, the kidney room, the urinary bladder room etc.Indications for radiographic examination
Indications for an esophagram include regurgitation, gagging or retching, dysphagia, cough associated with eating, as well as the presence of a mediastinal, cervical, or thoracic mass. The pertinent anatomy to remember is that in the cat the caudal 1/3 of the esophagus is smooth muscle.