Don't Panic. There are many things that you can do to locate your missing family member. Often it is these actions that result in the recovery of your missing animal. Please refer to the Lost Pet Recovery Tips Tab for information to help you start your search.
There are also various organizations that can provide additional assistance.
This site has additional information as well as a Lost Pet Help Directory that lists trained people who can help with phone consultations or in some cases on the ground assistance.
There are several State Specific organizations that can also be of great assistance.