Try the Comfort Zone Feliway spray for cats and spray inside the crate before you go. I have not tried the spray but have used the diffusers many times and they do work to keep the cats calm. I have heard the spray does the same thing and I know a couple people who spray the inside of the carrier before a vet visit.Google it and I believe most pet stores sell them and you can get them on Amazon.Not the cheapest thing you can get but effective. I have bought a couple other kinds that were less expensive and in my opinion the didn't work. Good luck to you.