Thanks for your inquiry! It is my understanding that you must have the domestic pet import permit arranged in advance if you would like your pet to have a very smooth transition through customs without having to wait additional time for processing.
The point of contact for this permit can be directed through this website, Vietnam Ministry of Agriculture and Rural Development. There is a small icon to the right of the page with a British flag. Click on this flag and the site will translated into English.
Also, if you would prefer one of PetRelocation.com's International Specialist (for Vietnam) to facilitate the relocation of your two dogs, including the necessary paperwork required, please let me know and I will be happy to have one of them contact you.
I wish you and your Staffies a safe and happy relocation to Vietnam!