Get a fresh sample and bring it with you in a plastic bag. If it's the day before, just put it in the refrigerator, it will be fine as long as it stays moist. Also, ask if they do fecals on site or send them out. You may want to call in advance and ask that question. I don't really care for vets that send it out. Be sure to get as much details as possible if your dragons test positive for coccidia or pinworms. A vet that doesn't know dragons may medicate for low amounts of coccidia when there is no reason. Those of us who do our own fecals usually do two or three tests and don't medicate unless levels are consistently high over a period of time. If they do give you medication, post or PM Tracie telling her details about the test results and dosages so that she can review and give her opinion. If I've learned anything from her, it's to avoid unnecessary medicating whenever possible.
If you are in a cold place, fill a sock with rice and put in the microwave being careful not to get too hot. This will stay warm for about an hour and make the ride more comfy. I always put my dragons in my jacket or sweatshirt so they stay warm with my body heat and don't get overstimulated from seeing too much motion outside the vehicle.