Are there any laws on purchasing a pet from a breeder? For example, are breeders required by law to give you a health certificate -- and are they required to have given the animals their vaccinations?
Some states do impose disclosure requirements on pet breeders. Pet stores -- many of which have been found to sell unhealthy dogs from puppy mills -- are generally subject to greater regulation than are independent breeders.
There may, however, be local or state laws intended to protect you; check with your state health department or consumer affairs department.
Even if the law does not require the kinds of reassurances you are after, though, there's nothing to stop you from asking for them. Whenever you buy a pet, you should have a written contract that spells out your expectations and the seller's promises. If health certificates and vaccinations are dealbreakers for you, be sure the contract mentions them in no uncertain terms.