Lock Richie Gray, who had returned to the Scotland fold, will also be absent for the three-day camp due to a calf issue.
Townsend had originally named a 40-man selection, including former captain Greig Laidlaw.
BREAKING | Edinburgh Rugby hooker Neil Cochrane added to Scotland squad after George Turner sustained a knee injury playing in Glasgow Warriors’ win at the weekend. Lock Richie Gray misses the three-day camp with a calf complaint #AsOne pic.twitter.com/sdju6OgrMd
— Scottish Rugby (@Scotlandteam) January 22, 2018
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