Regulations for transporting pigs...
Traveling With Your Pet
In order to cross state lines with livestock (whether it's a pet or not) you still have to follow the USDA guidelines. International travel is a bit different and that link is also included.
Some states require blood testing while others do not, some states require visible identification, like an ear tag, while others are alright with a microchip or none at all. Even if you're only passing through a state, you still have to follow the guidelines for each state you go to or travel through. Not every vet is certified to write a health certificate. So it is your responsibility to ask if he/she is credentialed to do so. That or, check the link below to find one that is able to write a health certificates for your pig. PLEASE CHECK FOR YOURSELF, DO NOT TRUST SOMEONE ELSE'S RESEARCH BECAUSE IT CAN BE THE DIFFERENCE BETWEEN LIVE OR DEATH FOR YOUR PIG!
This is the international link to see what the transport requirements are.
Travel regulations within the US. If your state is not listed, they may not require a health certificate to travel in to. However, whatever states you're crossing through or going to, may be different and their rules will need to be followed.
And finally, finding a vet to write/test for a health certificate.
Each state has a state vet, here's the 2014 state vet list sorted by state. Should you have questions or need additional information, this is the person that you would need to contact.