We haven't made any international trips with the cats, but Mini and Jasmine have flown interstate twice so I hope I can help.

If you haven't already bought a carrier, I'd look at one long enough for a small litter tray on one side and somewhere to sleep on the other. One mistake we made was using only the foam pad that came with the carrier. It gets extremely cold in the cargo hold and if we fly with the cats again, we'll put a favourite blanket in one side of the carrier for them to snuggle into to keep warm and feel safer. I wouldn't buy a carrier taller than Boo's head height when he's sitting up; I was concerned at the cats bouncing around too much in turbulence if they were in a tall cage.

Also pack his favourite toy or start acclimatising him with a stuffed toy to travel with. I think we were lucky because our cats travelled in the same carrier and had each other for support. Boo may get lonely by himself.

We opted not to sedate. The zonking out and possible inability to drink enough water during the flight turned us against sedation. As Neko1 said, if it's an option, do a trial run first so the dosage is correct.

We also sprayed the carrier with Feliway, which contains cat pheromones. It seemed to relax them a bit as their surroundings smelled safe and familiar.

And if you can, make sure Boo isn't loaded next to dogs or other loud animals that'll stress him with barking or other loud noises.

Hope this is helpful.