An ultrasound is a machine that uses sound waves to produce images of the interior of the body. Even though the machine produces sound waves, the procedure is silent since the sound waves are out of the range of human hearing.
During an ultrasound procedure, a transducer is gently pressed against the skin of the patient which causes the sound waves to enter the body. As the sound waves encounter fluid, blood, bone and organs, the sound waves are reflected back where the transducer detects them, and a computer forms an image. These digital images are stored on a computer to be saved and easily reviewed later.
For the transducer to make adequate contact with the skin, dogs and cats typically have to have the area of their body being examined shaved. Anesthesia is typically not needed for this procedure, as it is not uncomfortable or stressful. A typical ultrasound procedure takes 30-45 minutes and can be done while you wait.