I just did a search on CDC and APHIS web sites and these are the regulations:
How to Bring Dogs into the United States for Commercial Sale or Adoption
Importing dogs into the United States for resale, whether through commercial sale or adoption, is now covered under the Animal Welfare Act (AWA). Congress added this section to the AWA in 2008 and APHIS published specific regulations in 2014.
To import a dog into the U.S. for resale purposes, the animal must be:
•in good health;
•vaccinated for rabies and distemper, hepatitis, leptospirosis, parvovirus, and parainfluenza virus (DHLPP);
•at least 6 months of age;
Specific paperwork must accompany the dog on its trip to the U.S. This includes:
•a health certificate and rabies vaccination certificate, issued in English by a veterinarian with a valid license to practice veterinary medicine in the country of export; and
•an import permit issued by APHIS.
It looks pretty straight forward: permit, health certificate (certified healthy), and vaccinated. It doesn't look like quarantine is required for dogs unless going to states or US territories that are rabies free where there is a quarantine for every dog/cat.