You should know beforehand bulldogs can have minor but common health concerns, including cherry eye and skin allergies and require excellent veterinary care so before buying a puppy make sure to have the puppy checked out by a Vet. A reputable and responsible breeder will have a clear and transparent health guarantee listed on their purchasing agreement and give you 24-72 hours to get the pup examined at your own vet just in case there are any costly or life-threatening conditions outside the minor issues common to bulldogs that can be easily treated. Check to see if they will replace the puppy; refund you in the event something is untreatable. A responsible breeder will not only make sure your puppy has a clean bill of health but they will also have a screening process to make sure they are going to a good home.