Gracie May now wears soft fabric used for sleeper suits given to first-class air travellers after British Airways donated the PJs to ease her sweet itch rash at Horseworld, near Bristol.
The animal's life had been made a misery by blistering skin caused by bug bites, before BA and supplier Orvec came to her aid.
Richard Wyatt at HorseWorld said: 'We were surprised but delighted to receive the offer of a first class sleeper suit from British Airways for Gracie May.
'She's been hugely popular with our visitors since she came to HorseWorld in 2001, but we never expected she'd be flying in First.
'She's now the envy of our other rescued horses, ponies and donkeys.'