Blake (21) was forced off the field in the pre-season match against Southland in Gore on Friday afternoon, with what appeared to be a nasty injury to his right arm.
He was diagnosed with a dislocated elbow and had it operated on over the weekend, and his arm is now in a cast.
Although it is difficult to predict the exact length of time he will miss, he is likely to be off the paddock for six to eight weeks.
With the ITM Cup a condensed competition and finishing in October, Blake may struggle to get back on the field for Otago.
Blake has not had a great run with injuries.
The New Zealand colt was a wider training squad member with the Highlanders this season. He dislocated his shoulder in the final warm-up game against the Blues and had a late start to the season.
He never played for the Highlanders and was looking for a big ITM Cup season, but his hopes appear dashed.
Otago coach Tony Brown will not be calling in a replacement as he has plenty of options in the loose forwards.
Lee Allan played games on the openside flank last year, and Willis Scott, who impressed for Taieri this year, is a specialist openside. He is yet to play for Otago.
TJ Ioane and Gareth Evans are also options to wear the No 7 jersey.
Blake was the only major injury problem from the game against Southland, which Otago won 47-28.
Prop Tama Tuirirangi did not take the field against Southland and Brown said he was a 50-50 chance to take on Bay of Plenty at Forsyth Barr Stadium on Sunday in the opening round of the ITM Cup.
Tuirirangi picked up the injury against Tasman on August 4 in Nelson. He is a key man in the Otago scrum but Scott Manson and Craig Millar showed positive form against Southland.
Brown said he was encouraged by what he saw against Southland. Otago scored some nice tries and showed some steel on defence.
But Brown said there was still plenty to work on, and the side needed a full training week before the match against Bay of Plenty.
The Steamers will have a few players missing from their first choice line-up with the likes of Sam Cane and Brodie Retallick on All Black duty. Winger Lelia Masaga has gone to Japan and fullback Tony Arnold is playing in France.
Openside flanker Tanerau Latimer is coming off a huge season with the Chiefs and will still be on leave.
Bay of Plenty, which is in the Premiership, won the equivalent match last year in Rotorua.
