Dugan on Tuesday revealed he's battling a "personal" matter, which is not limited to drinking alcohol while injured.
Raiders coach David Furner said Dugan and Ferguson broke team protocol by missing a rehab session on Monday after the Raiders 32-10 loss to Penrith.
Furner said police were called to a disturbance at the house the duo were drinking alcohol at and have been stood down indefinitely while the club investigates the matter.
"The club has strong policies in place and breaches of these policies are taken very seriously," Furner said.
"We have stood both Josh and Blake down for breaches of these policies and will determine punishment once we have concluded our investigations."
Dugan apologised for his breach of club policy on Twitter and said he urgently needed to sort out an off-field issue.
"This goes beyond the drinking while injured. Yes I've broken team rules but for me it goes deeper and I plan on sorting it out," tweeted Dugan.
"I apologize to my team mates and the fans but this is personal and needs to be sorted out as soon as possible for me to move forward."
Dugan injured a rib cartilage in the Raiders' 32-10 loss to Penrith on Sunday, having battled a lip infection in the lead-up to the round-one match.
Last May, the Raiders stood Dugan down for drinking alcohol while injured.