The CDC (Center for Disease Control and Prevention) regulations require that dogs imported into the United States are healthy and are vaccinated against rabies. Dogs that have never been vaccinated against rabies must be vaccinated at least 30 days prior to their arrival. The dog/puppy must be at least three months old in order to receive the vaccine. They must be accompanied by a current, valid rabies vaccination certificate. A rabies vaccination is not required if your dog is imported from a rabies-free country.
The U.S Department of Agriculture, Animal and Plant Health Inspection Service (USDA APHIS), requires that dogs that are imported from countries where screwworm exist must be accompanied by a certificate signed by a veterinary official of the country of origin stating that the dog has been inspected for screwworm within five days before entering the United States. The certificate must state that the dog is either free from screwworm or was found to be infested with screwworm and was held in quarantine and treated until fee from screwworm.
Cats entering the United States are not required to be vaccinated against rabies.