Yes there is a similar "white coat" ceremony, and a similar oath.
Actually the oaths that MDs and DOs take vary as well. I do not think most people still ascribe to the traditional Hippocratic Oath. If you read it you'll notice it says that physiscians will not charge for teaching their practice, and that it will only be passed down within the family. It also says no to euthenasia, abortion and surgery. The modern Oaths have been greatly revised.