The 27-year-old was admitted to hospital on Wednesday, had fluid drained from his right knee and placed on an intravenous drip to treat an infection.
The Dogs remain hopeful the 2008 Brownlow medallist will be available for round one, describing the infection as minor.
"We see this as a minor set-back for Adam and we are looking forward to having him back at training next week," Bulldogs football manager James Fantasia told the club's website.
Cooney has been plagued with knee problems since his Brownlow triumph, but a strong pre-season has the Bulldogs hopeful he can return to somewhere near his best in 2013.
The Dogs host NAB Cup champions the Brisbane Lions at Etihad Stadium on Saturday, March 30.
Adam Cooney is a midfielder in AFL Fantasy. He averaged 75 points in 2012. Register your team in our AFL Fantasy hub.
