I'm a US citizen spending some time in the UK. While I've been in the UK, I've gotten a dog and trained it to be my service dog under US regulations since I intend on moving back and living there. I understand that the UK has different laws and regulations for service dogs, so my question is when I'm flying back to the US with my service dog, will I be asked for certification and other paperwork required for UK service dogs? Or is it just the requirements of US service dogs? The airline is United, and on their website they only require DOT paperwork. I'm just worried that when I get to the airport, they will require certain certifications for UK service dogs, which I do not have.