Canterbury are privately seething at the NRL's decision to slap them with a $20,000 fine after Josh Jackson was allowed to remain on the field despite showing signs of concussion.
The Bulldogs are certain to appeal the breach notice handed to them on Tuesday by the NRL's head of football Todd Greenberg.
The incident took place in the final seconds of the club's round two win over Cronulla when Jackson struggled to get to his feet after making a tackle.
He then got back to take his place in the defensive line without being treated by a member of the Bulldogs' medical team.
A club source said the Bulldogs are upset at the ruling because at the time their physio was treating another player and unable to attend to the back-rower before the full-time siren sounded.
Greenberg said the timing was irrelevant and imposed the fine, half of which is suspended, and said it showed how seriously the code was taking concussion.
"Today is a line in the sand and shows we're fair dinkum about the policy and how we'll police the policy," he said.
"It's our view the Bulldogs did not comply with the policy.
"Our view was he should have been taken from the field. The policy is designed to take players and place them in the care of the person most responsible, which is the club doctor."
Bulldogs CEO Raelene Castle said while the club was supportive of the league's concussion policy, it was at odds with the outcome.
"We don't agree with all the findings in the breach notice and, as per the process, will be using the next seven days to have those discussions with the NRL," Castle said in a statement.
A total of 27 players were taken from the field to undergo the newly-introduced Sideline Concussion Assessments (SCAs) in the season's first five rounds, with 14 returning to the field after being cleared of concussion.
Greenberg praised the clubs for the way they've embraced the changes and said player safety is at the forefront of the ruling.
"I genuinely congratulate the clubs for the first five rounds for the way they have adopted the policy," he said.
"We have players taken from the field when historically they wouldn't be."
Five clubs have so far been given "please explain" notices in relation to their compliance.
Greenberg said including the Jackson investigation, three of those cases were resolved with the NRL satisfied with the responses from Parramatta and Penrith.
Three others are still being probed, including another involving the Bulldogs and their decision to allow front-rower James Graham to come back onto the field in round four against Melbourne despite looking very groggy.
Greenberg refused to go into detail about the progress of the investigations but should the Bulldogs be found to have a case to answer, they could face the prospect of points deduction.
He also defended the match review committee for not punishing Gold Coast hooker Beau Falloon for his lifting tackle on Will Chambers on Sunday.
Melbourne demanded to know why Falloon wasn't sanctioned, a week after Storm prop Jordan McLean was slugged with a seven-week ban.
"Every club is entitled to ask questions," Greenberg said.
"The game has been around for a hundred plus years and there is always questions asked about various issues in the games.
"The important part is that the match review committee are independent and made up of experienced former players who are there to discharge duties according to the rules.
"You won't always agree with the decisions they make but the process is fundamentally correct," Greenberg said. AAP