A cat was found hidden in a cabin bag on board a flight leaving Glasgow Airport.
The passenger, who was taken off the British Airways flight, claimed she needed it for 'emotional support'.
However, only dogs are recognised as support animals on British Airways flights.
A spokesperson for British Airways said: "Cats cannot travel in the cabin but recognised assistance dogs are always very welcome and travel completely free of charge alongside their owners on board.
"Other animals will need to travel in the hold but will be just as comfortable in a carefully controlled environment."
Following the incident, Glasgow Airport assured passengers that the surprising discovery was not a security issue.
Their spokesperson added: "The woman presented her cat to our staff members at security.
"Because support animals can fly in the cabin of certain flights out of the airport, they allowed it to pass through.
"We suspect the woman forgot to tell British Airways she would be flying with her animal."