Ultrasound and X-ray are both useful tools in detecting neoplasms, but both rely on showing the outline of a neoplasm, and generally work only if there is marked enlargement of a normal structure. However, like any diagnostic test, it has its limitations. Because adrenal neoplasms may be small enough not to cause enlargement of the gland, these may be missed with both ultrasound and X-ray, and diagnosed only on clinical signs, or elevated levels of estrogen or its precursors in the blood. Here is a common scenario - ferret presented for clinical signs of symmetrical baldness. Ultrasound is scheduled. Well, as soon as the clinician walks in and sees the bald ferret - he or she is immediately geared to seeing an enlarged adrenal gland, and is likely to see one regardless of what the monitor shows. It's unavoidable bias, and a test whose outcome is so predestined, it's not valid. This is one of the reasons that I generally recommend going to surgery if the clinical signs fit the profile, and not waiting for ultrasound to be performed. Ultrasound and x-rays are good tools in the diagnosis of neoplasia, but only that. The statement that it always finds the tumor is patently overstating its significance. With kindest regards, Bruce Williams, DVM [Posted in FML issue 3601]