I’ve done the ATL–LHR trip with my cat before. She also needed meds, so cargo wasn’t an option. Delta let me bring her in-cabin under the seat in a soft carrier. Cost a pet fee, but it was worth it. The hardest part was paperwork, UK has strict rules, so make sure vaccinations and microchip are all set before you go.
Honestly, she handled the flight better than I did. Slept most of the way once we were cruising. Big relief
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