
A breeder is just someone whose bitch has had puppies!
I suggest you go to the
Kennel Club site, click on Discover Dogs, then Breeds (down the side), Toy group, Chihuahua (longcoat) and scroll to the bottom of the breed standard where you'll find breed club contacts. These will be the best people to help you get a healthy puppy. But you may have to wait some time, because not many chihuahuas are born each year. Good luck!