Hi,    
we just drove 18 hours to FL with our puppy who also gets motion sickness from the car. Prior to leaving he had very little water and food. I also purchased a puppy booster seat and I gave him a 1/4 of Benadryl which he licked and refused to chew. I must say he was quite comfortable in his booster seat. He slept and we took him out to potty everytime we stopped for gas. I read online prior to leaving that you should keep the temp in the car comfortable and crack a window to balance the noise. I was nervous at first traveling with our fur baby, but he did good for the first time in a car and he didn't throw up once.  Good luck!     |