The move was one of the options the Vikings were mulling this week as they assessed a recovery timeline for the turf toe Smith suffered in Sunday's loss to the Carolina Panthers.
Under rules the designation that started last year, Smith will not be allowed to practice for six weeks and can't play for eight weeks. That means the earliest Smith could be back in action would be Dec. 15 at home against the Philadelphia Eagles. He would be eligible to play the last three games of the regular season.
"Harrison is a key guy for us. It's definitely going to hurt not having him out there, but you've got to have that next-man-up mentality," CB Chris Cook said. "We all trust in Andrew (Sendejo), and his ability to play. He plays hard. He runs to the ball every day in practice, and I don't expect anything less from him in the game."
Smith is tied for the team lead with two interceptions, is third on the team with 41 tackles, including one for a loss, has three passes defensed, a fumble recovery and a forced fumble.
Each team is allowed only one use of the IR/designated-to-return transaction each season. Last year, the Vikings used it on Cook, who suffered a broken forearm.
Smith was in a walking boot on Wednesday, but that had changed to a hard cast and he was using crutches on Thursday.
Andrew Sendejo will start in place of Smith Monday night at the New York Giants.
In response to the depleted secondary, the Vikings signed CB Jacob Lacey, who was with the team during the offseason but released on Aug. 19. Lacey had arthroscopic knee surgery in early August and was expected to miss two to four weeks.
Lacey initially came to the Vikings as a free agent after spending 2012 in Detroit, and 2009-11 with the Indianapolis Colts.
Lacey started nine games for the Lions last year and has 36 career starts in 54 games.
BISHOP SETS ACL SURGERY
LB Desmond Bishop, who tore the anterior cruciate ligament in his right knee, has surgery with Dr. James Andrews scheduled for Tuesday.
That's the same surgeon that performed ACL surgery on RB Adrian Peterson on Dec. 30, 2011. Peterson returned for the start of the 2012 season and was named the league's MVP after rushing for 2,097 yards.
"The first person who I talked to was Adrian about it, looking at his whole timeline so that's what I'm kind of in competition with right now," Bishop said Friday before the leaving the locker room on crutches. "I believe he got his surgery after the injury six or seven days after. I think mine is going to be eight, so I'm a little upset about that. Going forward, I'm just going to try to keep at the same pace he had. That's where I'm kind of channeling all my focus is to outdo him."
Bishop signed a one-year deal with the Vikings in June, but he said he isn't contemplating his future with the team, although he has "no doubt" that he will be able to play again.
The weakside linebacker was just starting to hit his stride with the Vikings, making his first start Sunday against the Carolina Panthers before the second-quarter injury ended his season.
"It's definitely unfortunate. I felt like I was coming, really getting into my groove. I've always been in my groove, really, honestly. It's just kind of the way life is and the way things go sometimes," Bishop said. "There's nothing really you can do. It's out of my control. The only thing I can do is focus on what I can control and that's my rehab and coming back better."
Bishop tore the hamstring in his right leg last year, but he said that and a minor lateral collateral ligament injury in that knee didn't have anything to do with his injury Sunday. He said the hit came from a failed attempt by a Carolina Panthers tight end to cut block Jared Allen.
"He tried to cut Jared and Jared jumped over him. I was behind Jared and had no idea he would come under Jared that fast and he rolled right into my leg and trapped my foot and I couldn't get out and it twisted," said Bishop, who let out a yell loud enough to be heard in the press box as he walked off the field.
"… I was just frustrated being hurt. That was my biggest frustration initially. I didn't really know exactly what the injury prognosis was. I was just angry that I was freakin' on the ground and couldn't get up."
"I thought he had a great game. It's the best game he's had as a pro," Priefer said. "It's a young season, young career. But he punted well. He held well. He kicked off well. I was excited about the way he played on Sunday."
Tim Yotter is the publisher of Viking Update. Follow Viking Update on Twitter and discuss this topic on our message boards. To become a subscriber to the Viking Update web site or magazine, click here.