If your cat is cooperative, no anesthesia or sedation is needed to perform ultrasound on the heart or the abdomen. If biopsies are to be taken, a short-acting anesthetic will be needed to help prevent complications. In most cases, yes. It is imperative that the hand-held probe make complete contact with the skin. Sometimes the hair can be moistened with alcohol, but most studies require hair removal.
Air is the enemy of ultrasound waves.
Since the lungs are air-filled, they cannot be studied. The exception is a mass that is located within the lungs. Bone also stops ultrasound waves, so the brain and spinal cord are not seen with an ultrasound study. Obviously, the bones are also not examined with ultrasound. Since an ultrasound study is performed in real time, the results of what is seen are known immediately.