Ultrasound equipment uses very high frequency sound waves to produces moving images of parts of the body and as such is completely harmless to tissue and organs. We are using this imaging technique more and more frequently to look at internal organs such as liver, kidneys and heart as well as the usual reason everyone expects us to use it - to determine if puppies or kittens are present.
We have two ultrasound scanners; this one is our most recent addition.
The major advantage of ultrasound is that it is safe, relatively quick to perform and is usually done in the conscious patient. We normally have to clip some hair to enable good probe contact though.