We are paranoid parents. I didn't realize until we got the cats home how worried both of us had been that the visit to the vet would result in their complete trauma, and possibly news of some terminal illness causing the sneezing fits. Or that after one trip to the vet they'd never trust us again.
The only thing that seemed to bother them was being trapped in individual cardboard boxes, unable to see each other or what was going on around them. They're curious enough that they don't think to be particularly scared, they just want to check everything out. Including all the cupboards in the Vet's office. I solved the cardboard box problem by buying a carrier big enough for both of them (only just), so that on the way home they could be together and check out the world as well.
They got inspected, and had a giant worming pill each shoved down their throats, and were sent away with the verdict of a case of the sniffles that will clear up on it's own. We were given antibiotics to give them just in case, also to prevent secondary infections, we get to capture them twice a day and squirt orangey medicine down their throats with a needle-less syringe. Again, something that seems to traumatize them for all three seconds. I wish I had such powers of recovery.