Lepto shots can kill a Yorkie so I would find out if you live in an area that it is
really needed. Sorry to say, I would not just trust a vet's recommendation. Vets have been giving shots for many things that a dog does not need. I feel that we need to take an active part in deciding what our little ones need.
On this website you can see the AAHA recommended vaccinations for your dog. You will need to print it off but I think this is a great publication.
http://www.aahanet.org/resources/guidelines_canine.aspx