Some yorkies coats will NEVER reach floor length and some need to have their hair cut every couple of months to keep them from tripping on it

Lady was 2 in november and Jess will be 2 in April and they still have what I call,puppy length coats and Im not expecting any miracles at this point

Their coats are silky,shiney,SO easy to comb etc,but it just wont grow.
Iv just ordered a hair growth stimulator which is basicly essencial oils (about 10 different kinds) essencial acids (another 6 of those) and lots of different vitamins and minerals..Im hoping this will do something even if it only grows another inch.
Iv posted a couple of pictures so you can see how short their coats are.The first picture is Jess and the second is Lady.2 yorkies whos hair wont grow..now what are the chances of that happening!? lol (just my luck!).