if the dog is unwell, it's your call weather you will take it to the vet or home. They will not quarantine it. Sometimes they even not checking the dog, only the documents.
before your dog will fly , you need to get health certificate, fully vaccinated so that you can get export permit. Airlines will not allow you to take your dog without it.
there's no quarantine for animal when arrived here in Thailand. You just need an import permit and you can take out the dog with you. I know because I'm a pet shipper here in Thailand
Been to da nang few days ago, I only stayed there for few hours and back to Thailand, everything was so smooth. And no one also asked for my return ticket
No need. US passport doesn't require a visa here in Thailand. Lay over doesn't require a visa as well as long as you don't go out of the immigration ( depends on what country)
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