Another trick that seemed to help was just putting the cat and carrier in the car and just driving around the block before coming home. Eventually, see if you can take her up to say, 7-11 and get a cup of coffee, then bring her home. Maybe even farther if necessary (my vet hospital is quite close by and a short trip was good enough for car tolerance training). One in a while, I take one up to 7-11 just for maintenance.
It doesn't stop 100% of the crying, but it's a lot better, the crying stops sooner, and I don't have any of them wetting the box any more.
It doesn't stop 100% of the crying, but it's a lot better, the crying stops sooner, and I don't have any of them wetting the box any more.