Hi
I have a 3yr old small yorkie, her weight is 1.5kg. Is she too small to breed with?

http://www.thekennelclub.org.uk/item/199

As important you should consider the rest of the breed standard as well as size to make sure she is a good example of her breed before even considering breeding :)

1.5kg would be under three and half pounds so, yes: FAR too small to breed from.  My Mum bred and showed Yorkies for years and would never dream of breeding from anything under five and half pounds at the very least.  I cannot begin to tell you the problems of breeding from a bitch that small.  It's not just difficult whelping - the problems can be life-threatening. 

Also, the smaller Yorkies get the more they seem to suffer from herediatry problems - like Perthes disease, etc.  Just enjoy her for what she is :-)

Debs

Thank you so much for your advice.

Maia
I keep two toy breeds.  Breed standard is up to 6lbs for one and 7lbs for the other.  I have to say that the little ones are difficult enough to breed without looking for trouble!  I use girls at the top end of the breed standard weight guide, and I use tiny boys for stud.  I would never breed from a bitch as tiny as yours.  You would never forgive yourself if anything went wrong.  I like my bitches 5.5 - 6.5 lbs in weight, and you still need the odd C-section.  I would say don't put her in danger.  Look at the width of her pelvis, and you will know why.

My friend has a yorkie about the same size as yours and she was going to breed her as well.   I introduced my friend to a yorkie breeder, who shows hers, and they they said its was a big no, no as she was far too tiny.    My friend immediately made arrangements to have the bitch spayed and she is a great little dog, will now be about the same age as yours it.