
I would contact the breed club for the breed, and if they have a website you should be able to find their code of ethics. Also deatails of which health problems are tested for.
The pup should be registered, and it's parents hip and eye results will be printed next to their names.
The breeder sho7uld also give you a Pedigree, normally five geneartions, usually written by themselces, though some opt to purchese ready printed ones from the Kennel Club.
The pup should have been wormed at least twice, and not be under 7 to 8 weeks old, though in some Toy breeds breeders prefer to keep the pups until aroun 10 to 12 weeks.
If you contact the KC with the Dams name, they will be able to tell you when her previous litters if any were born. She should not normally have been bred from more than once a year, unless there was a single pup in last litter.