Muhammad Ali released from hospital

— -- Muhammad Ali was released from an undisclosed hospital Friday, Ali family spokesman Bob Gunnell said.

Ali, the former three-time heavyweight world champion who suffers from Parkinson's disease and makes few public appearances, had been hospitalized for continued treatment for a severe urinary tract infection. It was the second time Ali had been hospitalized in the last four weeks.

"He's home and resting and glad to be out of the hospital,'' Gunnell said.

Ali was initially hospitalized on Dec. 20 with what was originally believed to be a mild case of pneumonia. However, Ali was later diagnosed with a urinary tract infection rather than pneumonia.

Gunnell said Ali, who is from Louisville, Kentucky, was at one of his homes -- he and wife, Lonnie, have homes in Louisville; Paradise Valley, Arizona; and Berrien Springs, Michigan -- and is looking forward to celebrating his 73rd birthday with his family on Saturday while cheering on the Louisville men's basketball team in its game against Duke.

Gunnell said the Ali family "greatly appreciates the outpouring of support and continued well-wishes" for Ali.

Ali retired from boxing in 1981 and has focused on social causes since then, traveling the world on humanitarian missions. The Muhammad Ali Center in Louisville is dedicated to Ali's humanitarian causes and showcases his boxing career. 

Information from The Associated Press is included in this report.