There was never any question that we wouldn't bring our cats with us when we relocated - they were a part of the family that we weren't going to leave behind.
Our first port of call was our local vets, who initially weren't that helpful, merely directing me to the DEFRA website. However, after researching what might be needed myself, I contacted some pet relocation companies for further advice and quotes.
We knew the process wouldn't be cheap, and it actually ended up costing more to put the cats on the plane that it did for my own plane ticket! However, we were pleased we had done our own research, particularly when our relocation advisor came back with a cost that was 3-4 times the cost we had been quoted by local UK companies, as well as incorrect advice that the cats would need to go into quarantine. In the end, we decided to make the arrangements ourselves.
By obtaining Pet Passports for both cats, and certifying their rabies vaccinations and microchips, under the European PETS initiative (Pet Travel Scheme) they are free to both enter and leave the US (and other EU and recognised countries) without having to go through quarantine procedures. The passports were organised by our local vet in Cardiff, for a small cost.
We liaised regularly with our chosen pet relocation provider (we eventually selected Pet Air UK), and they patiently answered all of our neurotic questions and queries. We had to choose the best destination airport for them to fly into, in the end deciding on Philadelphia as it seemed to be better set up for receiving small animals. We also decided to pay an extra fee to have all the customs paperwork dealt with on our behalf at the US end. The cats actually flew on the same flight as me, and having to deal with the lengthy, protracted customs paperwork process (involving travelling back and forth between two separate buildings of the airport), would have been challenging, frustrating and tiring after an 8 hour flight and a 90 minute queue at passport control...
Because the flight was on a Monday, the cats were actually collected direct from our home in Cardiff on the Friday beforehand, and kennelled over the weekend by Pet Air UK in Windsor, nearer the airport. They took care of all the pre-flight health checks, the outgoing paperwork, and getting the cats safely boarded. I just had to worry about getting myself to the airport.
The cats each had their own custom-built wooden cage (Ash's had to be made slightly bigger than normal because he's a big heavy boy). We weren't able to leave them with their favourite blankets, but I could give them a small square of fabric each that I'd kept under my pillow, so that they at least had something of comfort that smelt of home. I made sure I packed their blankets and a few toys in my hand luggage, and their beds and scratching post went in the air freight. The cage itself was lined with absorbent puppy pads and warm vet fleece, and they had a water bottle attached for the journey.
On flights, animals are placed in a heated and pressurised part of the hold - because it's warm and dark, allegedly they sleep for most of the journey (at least, that's what I've been telling myself).
To read the rest of their relocation story, keep following along!