I assume you mean for Winston?
I would recommend NOT using gravol or valarian for two primary reasons: (I realize you di not ask about valarian but the same advice applies)
- Gravol is a powerful medication (even 1/2 is a lot for an animal) and it can over sedate them and they become confused and can choke on something or smother on a pillow or something in their carrier
- Very often, these meds - both of them - affect the cat or dog in a reverse manner in which they are supposed to, ie a pet will become very hyper and you will have a yowling or barking animal for the entire trip and one who is unhappy and scared. It is not worth it!!
I have used either Rescue remedy or cocculine , the latter more often. It was suggested by my vet and is available in any health food store. It has no adverse effects and is for anti-nausea (like gravol) but tends to make animals sleepy. However, I would advise you to talk with your vet before giving your pet ANY medication - even one from a health food store since I do not know what other meds your pet might be on and your vet will know your pet's history.
I have seen the effects of gravol and valarian given to cats who had no experience with it - members of their family (ie , small children) arrive in our ER badly scratched after the cat because s/he was so so hyper!! Of the 2 substances I have mentioned here, I tried them out on my pets first before taking them anywhere. You do not want to be in a moving vehicle or an airplane and discover that something you administered yo your pet has had the opposite effect of what you wanted.
Now, I rarely give my pets anything when travelling. The best way to is to get them accustomed to it when they are young so they are used to travelling so you do not require medications.