No Yorkie should be given Lepto unless you live in an area that has a lot of wildlife or high potential for the disease and even then the AAHA does not feel strongly about giving this shot.
http://www.canismajor.com/dog/lepto.html
Here is a website with vaccine recommendations:
http://www.aahanet.org/2006
Go down the page and look for 2006 AAHa Canine Vaccine Guidelines