Spears is very close to her father.
He was the one who helped save her life back in 2009 when he was made her conservator by a court, a role which he still serves to this day.
"My father saved my life," Spears once explained to the Daily Star. "I probably wouldn't be here if it wasn't for him … I owe him my life."
MGM Resorts International President Bill Hornbuckle said in a statement, "All of us at MGM Resorts wish Mr. Spears a speedy recovery. We wholly understand and respect Britney's commitment to her family and believe that her place is with them during this important time."
Early in 2018, Spears wrapped a four-year run at Planet Hollywood's Axis Theatre, which helped revive her career.