I think it all really depends on the type of pet. The biggest challange will be to find an airline that will allow you to bring the pet internationally. I believe most airlines have specific requirements on the types of containers that you are able to carry your pets in as well. There are quite a few websites online if you search "importing pets to USA." This is what I found on one website.
Dogs must be free of disease and be vaccinated against rabies at least 30 days before they reach the USA. Puppies younger than three months and dogs in rabies-free areas such as the United Kingdom are exempted, however. Unvaccinated dogs will be inoculated on arrival and confined for 30 days at your expense.
Cats must show no signs of disease and rabies vaccination is required in most U.S. states.
Birds are quarantined for at least 30 days in a Department of Agriculture facility, again at your expense. You must reserve quarantine space in advance and obtain a health certificate for the bird.
If it's a rare animal you might want to check and make sure that you are actually able to bring it into the United States ahead of time as well. This is also a pretty good PDF file that I found online that tells more about importing animals into the US.
http://www.customs.gov/ImageCache/cgov/con...pdf/v1/pets.pdfHope that helps some...