I have been studying for years & think i've decided not to risk it w/my girl. I am happy to share what I've learned though
This site has a ton of info just read everything
Click Here
Its based on Chihuahua but most still applies
This article intriged me
Click Here
I decided that I would pay a stud fee to another hobby breeder that did stud. Most are about $500. but I figured that Not have to worry about unplanned pregnancies, stud behavior, etc. And I would use the $ I would have used to get a male to get a second female-more puppies
A 5-6lb female is I think what most agree is exceptable & saught after by buyers. A 3-4lb male as stud. Buyers are looking for a smaller dog to easily take everywhere, but breeders have to not compromise the health by trying to get micro dogs. I was going to take my girl for a ears to tail check up & run all nesseccary tests w/my vet to ensure I have a healthy girl. And chosen stud would have same. My girl is about 4 & a half lbs & even though people are breeding them successfully w/3-4lb males (or smaller) She just seems so tiny to me that I cant imagine it. Of coarse I think of her as my child & thinking about taking her to have sex makes me sick at my stomach

I think you definately have to care for your pets but as a breeder there has to be more of a this is a animal/dog to do it, because the way I love my girl it really is hard for me to imagine. Not to say i'd never if I get in a different frame of mind about it
A breeder I ran into when I was looking for pups said she lets her 2 males both breed each female

& she wonders why she lost her AKC-Daaa. That is wrong you cant register dogs to a mom & dad when the pups have 2 dads. All she wants is bigger litters more $$$ not worried about the quality of the dogs life or pups. Makes me mad to think about it. The people like her make me feel like I should breed-the right way. But of coarse she sells yorkie pups for $600-$800 so... I have went to many yorkie site & they usually state the mom but when i try to guess the dad one pup looks like one & one like another & one like mom hmmm.