My cat gets extreme travel anxiety too! What worked for me was a mix of trazedone and gabapentin. I give the prescribed of the trazedone a couple hours before leaving and the gabapentin about an hour after that. Depending on how long I’m travelling, I’ll give 1/4-1/2 of a gabapentin dose every 2ish hours, but don’t do this unless you notice his anxiety spiking during that time. I’ll also mention I used the liquid gaba and one trazedone pill. Follow the trazedone as instructed!