Canterbury captain Josh Jackson is set to miss up to four months on pre-season after undergoing shoulder surgery.
The Bulldogs captain required stabilisation on his right shoulder but is expected to recover in time for the 2019 season opener.
Playmaker Kieran Foran will require two more weeks in rehabilitation following surgery on his toe and wrist.
The 28-year-old made 12 appearances for the Bulldogs in his first season at the club before being ruled out for three months due to injury.
Centre Kerrod Holland has also gone under the knife to address an ankle injury and is expected to rejoin the main group by December.
Second-rower Raymond Faitala-Mariner has been sidelined since playing for New Zealand in June but is expected to be fit for the start of pre-season on November 1.
Adam Elliott (wrist), Marcelo Montoya (hamstring) and Matt Frawley (foot) are also likely to be ready despite addressing minor concerns.