Meanwhile, former captain Easton Wood has also suffered a hamstring injury, although it is less severe than Jong's.
"Unfortunately from training today, Lin has suffered a high-grade hamstring injury," Bulldogs medical services manager Chris Bell said.
"It was during our match simulation session and he pulled up after accelerating.
"We're going to work through a process with Lin over the coming days to determine the extent of his injury and his return to play plan."
