Ask about the breeder's experience:
As with any job that requires knowledge through hands on experience, you would
want to know just how long this breeder you've met has been doing his job.
You can also ask just how long he's been breeding mastiffs and if he's a member
of any breed clubs.
Ask for the Health History of the Pups:
You should find out if the parents of the pups have been checked for diseases
associated with Mastiffs. Major issues for the mastiff breed are hip dysplasia and
gastric torsion.
Your breeder might have opted to have his dogs undergo tests for these problems
as well as elbow dysplasia, thyroid tests, and DNA tests for progressive retinal
atrophy to ensure that the chances of the dogs' offspring inheriting the genes for
these problems are lessened.
Also ask if the puppies have had their shots and have been de-wormed.
Ask About the Breed's Characteristics:
You can double check the reputability of American mastiff breeders by asking
questions about the mastiff's characteristics.
A good American mastiff breeder should be able to tell you a lot of information
about the breed - from the typical characteristics, to their opinions on what
family lifestyle would be better with a mastiff pet included in it.
Ask About Return Policies:
Would you trust someone who would not have the willingness to replace or refund
you in the case your puppy suddenly gets sick right after you take it home? Not so
much.
A good breeder will be willing to take back the pup if you suddenly find out
that you're not up to the task of taking care of the dog. It's a pet, not a product
after all.
That should help you out...