flying domestic with dog, documents list (for my cousin)

I dont have pet but my cousin asked me to help her fly with her dog from Don Mueang to Phuket next month, so I research a lot. Here is the list I make for her, maybe useful for others. First is health certificate from vet, need to show at counter. They say it should be issued recently, like within 10 day before flight, check with airline. Second, vaccine record, rabies must be on it. Third, copy of dog ID or chip number. The airline staff check the chip number sometimes, so bring the paper. Crate. Size matter a lot. Cousin dog is Shih Tzu, 6kg, so she can go in cabin if the carrier fit under seat, but the airline measure the carrier not the dog. My cousin bought one too big, she must buy new one. Waste of money. Also one thing I didnt know is that some airlines have rules for flat face dogs, cabin is not allow for certain breeds in hot weather, or sometimes they only take in cargo. Shih Tzu is flat faced too, so still check. Last, print everything and put in plastic sleeve. The counter staff is not nice if you search the phone while they wait. Trust me, I stand behind the cousin in the line and she is not happy at all. Good luck to your dog and the flight.