I would talk to your vet. When my husband moved here from Vancouver and brought his cat Kaliban we sedated her. Even though she was going to be under the seat. The vet gave her a med called Acepromazin. I think that is how it is spelled. It doesnt' totally knock them out but it takes the edge off and lets them sleep more. It helped her out a lot. I think he withheld food for 12 hours......I don't remember if the water was the same amount or not.

Denyce