Surgeons have transplanted a pig’s heart into a dying man in a bid to prolong his life – only the second patient to ever undergo such an experimental feat. Two days later, the man was cracking jokes and able to sit in a chair, Maryland doctors said Friday.

The 58-year-old Navy veteran was facing near-certain death from heart failure but other health problems meant he wasn’t eligible for a traditional heart transplant, according to doctors at University of Maryland Medicine.

“Nobody knows from this point forward. At least now I have hope and I have a chance,” Lawrence Faucette, from Frederick, Maryland, said in a video recorded by the hospital before Wednesday’s operation. “I will fight tooth and nail for every breath I can take.”