Hi,
I take my dog (33kg) France to USA each year for a 6 month stay.
Things I have learnt,
Try very hard to arrange a one sector non stop flight.
If the dog has not been in the UK for over 6 months, I’m sure there is a quarantine issue.
Cost of my dog on VS or BA is about $1500 one way!
Most vets do not like the idea of calming drugs but I have used herbal stuff, I think it works.
Make sure there is plenty of water in a special non spill bowl and attach a plastic bag with some dried food on the outside of the crate with a note of when he was last fed/watered in case of delays.
Leave a part of your clothing (unwashed) in the cage as a comfort toy.
Give your dog plenty of exercise immediately before the flight.
For my dog’s safety, it scares the hell out of me every time but it has to be done.
Good luck