
My friend who's a vet said that we can give my toy poodle the non-herbal Nytol to prevent car sickness. We give Roxy half of one, but obviously the dosage would be different for a Rotti. Perhaps she could speak to her own vet about what dose to give.
So far, it seems to work for Roxy, but I only give it to her on longer journeys. She doesn't mind going in the car, it's just that it makes her sick.