you've gotten some very good advice here but no one has yet mentioned what to look for in a healthy pup.
Be sure that any dog you get has a Health Guarantee, and that the guarantee covers Liver Shunts (Systematic Poral Cavel Shunt), Legge Perthes, as well as several other genetic problems. The guarantee should be for a MINIMUM of one year (I myself gurantee for 7).
Be sure to research the breeder, ask for references and CHECK them.
I would recommend that you go to a show breeder and not buy out of the paper or from some one who doesn't at least belong to a Breed club.
Ask the breeder questions. A GOOD breeder will welcome your questions and answer them all. They will also be very wary if you DON'T ask questions.
Buying from someone who has been in the breed for many years and shows is certainly not a guarantee you'll get a healthy pup, but the truly GOOD Reputable breeders stand behind their dogs, and their association with you won't end when you pay for your pup and drive down the road.
You'll pay more initially for a pup from a reputable show breeder, but in the long run you'll pay a whole lot less in vet bills.
Also, if you come across someone that is going to guarantee that the puppy will stay under a certain weight ... RUN. No one I know would do more than guesstimate.
Tinies (some call them teacups...grrrr) are sure cute, but remember this, they cost more initially and can potentially cost you LOTS more in vet bills. Everything from simple loose stools on down the list is an EMERGENCY for a tiny. They simply don't have the reserves of their more normal sized siblings.
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Joan
Responsible Breeders spay/neuter Pet puppies.
Statistically, the average breeder remains in a breed for five years. The mark you leave on that breed, good or bad, is entirely up to YOU!