Hi I have a Small and a Medium
Below is the MD size chart info.. Hope that helps
The Small fits most Yorkie babies unless they are very tiny .. then they would need an XS. Thanks so much!!
S25cm ( 10 inch )32cm ( 12.5 inch )18cm ( 7 inch )6-8 lbs
http://www.monkeydaze.com/help/imgs/0.gifM30cm ( 12 inch )38cm ( 15 inch )21cm ( 8.5 inch )9-12 lbs