It is also very important that whatever breeder you choose health tests the parents to make sure they do not pass on any genetic conditions to their puppies. That is usually one way to differentiate between a backyard breeder and a reputable breeder as byb's are all about profit and cut costs.
By health testing, I don't mean a wellness check by their vet. All breeding dogs should have bile acids tests to screen for liver shunts, orthopedic examinations to make sure they don't have luxating patellas, eye exams, thyroid panels, etc. One only has to read the Health and Emergency sections here on YT to see all the Yorkies who are battling genetic conditions.
It is very important that any prospective breeder be able to discuss genetic illnesses Yorkies are prone to and the steps she has taken to make sure her lines are free from them. She should be able to show you results of bile acids tests, knee exams, etc.
Just remember, many of the "genetic time bombs" may not go off for years. My Lady was perfectly healthy for the first four years of her life. She now has epilepsy, diabetes, hypothyroidism, just to name a few. :eek: That's why a breeder must really know her lines and the background of all the dogs she breeds as they may not show symptoms of disease until after they have produced puppies.
Remember, a backyard breeder doesn't have to be literally breeding in her backyard. Many keep them in darling little nurseries in their homes. Backyard breeders breed pet quality dogs who are not to standard and don't do health testing and genetic screening.
The best way to evaluate a breeder is to look at the YTCA's Codes of Ethics and Conduct and see if a breeder follows them:
Yorkshire Terrier Club of America