Some breeders, specially in USA, refer to shipping policy. I wounder: what is that?

How can I as a breeder have policy about shipping when it´s not up to me how to transport animals. To and from Sweden there´s not so many ways to transport mice. By air it´s not allowed, no company will take rodents. By buss same - no company allow rodents. So it´s only train, car and boat (some ferries don´t allow rodents eighter).

Sorry for bad English!