The former Lockerbie Academy student, who grew up in Johnstonebridge, requires ongoing assessment and treatment on a mild posterior thigh strain – with Scotland’s Six Nations opener against England 12 days away.
The Glasgow Warriors centre sustained the injury when his side beat Racing 92 on Saturday and it could see him lose out on a spot in Vern Cotter’s 35-man squad.
Dunbar, who missed out on last year’s World Cup, will hope for a speedier recovery this time around.