The team also said it had no additional details to release and did not want to speculate on how many OTAs Foles could miss.
"Our thoughts and prayers are with Nick and his family," coach Doug Marrone said. "He knows, like anything else, that we're here for him."
Foles, who signed a four-year, $91 million contract with $50.125 million guaranteed in March, had attended the team's first three OTAs. The Jaguars have four voluntary OTAs next week, and their mandatory minicamp is June 11-13.
"The football part, we'll just figure that out," Marrone said. "That's an easy part. We'll split it up and go out there and take reps and rotate them around."
Foles spent the past two seasons with Philadelphia and stepped in for injured starter Carson Wentz each season. Foles led the Eagles to a Super Bowl LII victory over New England and was named the game's Most Valuable Player.