"They were crazy with joy. They thought they'd lost her after an absence of nearly a month," one of the workers, Joelle de Becker, told AFP.
The collar also saved the cat from an ignominious end usually reserved for four-footed illegal immigrants arriving solo in France. The head of the regional state veterinary service, Regine Marchal, said that unidentified stowaways are usually euthanized.
But the U.S. owners sent a photograph to confirm it was their Emily, as well as her vaccination records.
In the meantime, the cat is being kept in quarantine, where it will stay for around another 30 days before being sent back home.
"Now we have to see if the cat will go back alone or accompanied, and who is going to pay its plane ticket," Becker said. "We're ready to do a collection so she is reunited with her owners."