The coggins exam is probably the biggest scam in the horse industry. The only thing a coggins shows is that the horse was negative for EIA at the exact moment it is pulled....and that is all.
That said, as someone else posted, in Texas it is required everywhere. So I pay my 30 bucks and get it done.....but I grumble about it....a lot.
I DO know that without it a state can impound your horse and charge you by the day. OP, don't know of ANYWHERE that you can get a one week turnaround on a Coggins! The best I've ever done is 3 weeks, and that was when I tested in February.
For those who don't know, Equine Infectious Anemia is a form of virus similar to Aids. It is not transmittable between horse and human, but a POS result of the blood test will result in the state destroying your horse.