The Western Bulldogs have suffered a cruel blow as running defender Ed Richards has been ruled out for up to six weeks after scans revealed a moderate hamstring strain.

Richards suffered the ailment during the third quarter of the Dogs' Round 12 loss to Geelong at Marvel Stadium last Saturday night.

Senior coach Luke Beveridge was initially confident post-game that Richards had avoided significant damage, however, the rebounding backman is now likely to miss more time than originally anticipated.

Western Bulldogs Head of Sports Medicine Chris Bell confirmed the news to the club's website.

"Unfortunately, in the third quarter of the game, Ed suffered a hamstring injury," Bell said.

"Scans have confirmed that this is a moderate grade injury.

"Ed has already started attacking his rehab, with us hoping to get him back in the next 4-6 weeks."

Richards' setback comes shortly after fellow backman Jason Johannisen was dealt a savage blow of his own, suffering a high-grade hamstring strain with tendon damage in Round 10, with the 30-year-old likely to miss the next 7-8 weeks of the season.

Aside from Richards, midfielder Toby McLean represents the other notable Bulldogs injury issue to come out of the weekend, injuring his back during the Dogs' VFL outing.

"From our VFL game, Toby McLean has suffered some acute low back pain after a tackle," Bell said.

"Scans have confirmed that he has an area of bone overload in his back that will need some time to settle.

"Once his acute pain improves, we will confirm his return to play plan, but expect him to miss some footy over the next month."

The Bulldogs play Port Adelaide and North Melbourne before their bye in Round 15.