Mulligan has been in poor health for years as the result of decompression sickness (the bends) from a diving incident, and last year suffered a heart attack. No word on what specifically lead to his being admitted to the hospital.You always hate to hear this kind of thing and I know that those who saw him in his prime consider Mulligan one of the all-time greats.
To me, personally, he is another guy that I know based on his reputation far more than having actually see him work kind of like Nick Bockwinkel, Larry Zbyszko, and Stan "The Lariat" Hansen. In fact the only time I specifically recall seeing him was from some Florida promotion that came on at the very end of Joe Pedicino's wrestling block.
It should also be noted, as most reading this most likely already know, that Mulligan is also the father of Barry and Kendall Windham. He also is part of the concussion lawsuits against WWE that has led them to countersue some of their format talent.
My thoughts and prayers are with the entire Windham family.