It took Marcus Bean's first goal for the club, after Lopez had opened the scoring in the third minute.
Bean's equaliser came three minutes from half time, giving the U's a valuable point.
There were more injury concerns though, as Freddie Sears and David Wright suffered hamstring problems.
Dunne made three changes to his starting line-up, bringing in Gavin Massey, David Wright and new loanee Elliot Lee.
The West Ham striker signed earlier in the day and went straight into the team for the game in Shropshire.
The home side started the game on the front foot, getting into the U’s final third and volleying over the bar on two minutes.
A minute later and they went ahead, with Christian Lopez scoring with a powerful header that gave Sam Walker no chance.
Shrewsbury were allowed far too much space down the U’s right hand side and Adam Reach had time to look up and pick out Lopez with his left foot cross.
The first effort for the U’s came on eight minutes, with Clinton Morrison holding the ball up and rolling it into the path of Elliot Lee.
Without taking a touch, the West Ham loanee shot with the outside of his right foot but there wasn’t enough curl on his effort and the ball went well wide.
At the other end, Jacobson got free from a left wing corner for the hosts but couldn’t guide his unchallenged header on target.
Freddie Sears shot well over the bar for the U’s following a good move by the U’s, with Lee, Gilbey, Bean and Massey all involved.
As the game flowed from end to end, Luke Garbutt had to be on his toes to head clear from another cross, heading clear with Lopez lurking at the far post.
The U’s injury woes continued midway through the first half when Sears pulled up with a hamstring problem and instantly knew he could play no further part in the game.
The ball didn't leave the field of play for a few minutes so the U’s were a man down until Craig Eastmond was able to replace Sears.
He was a spectator for the best move of the game, as the Shrews cut through the U’s and Walker had to dive full length to push away Taylor’s shot from the edge of the box.
Jacobson then had a shot blocked by his own player and a volley from Summerfield flew wide as the home side looked to add to their early goal.
Then, three minutes from the break, the U’s got a break of their own, as Marcus Bean’s shot made its way past Weale and into the bottom corner.
Morrison had held the ball up well again and rolled it into Bean’s path. Bean shaped his effort towards the far corner but Weale really should have done better with his effort to keep it out.
It was the former Brentford midfielder’s first goal for the U’s and it gave them an equaliser that saw the U’s go in at half time level.
Joe Dunne sent his team out for the second half determined to get that elusive win and it was the U’s who had the better of things early on.
Lee was creating chances for himself, first shooting wide after turning his centre half and then having a shot deflected for a corner.
Wildig shot well over from the edge of the box on fifty six minutes but the U’s returned to the attack on the hour, with Eastmond denied twice in the space of a minute.
First, a strong tackle from Winfield prevented his shot reaching Weale and then the home keeper saved a shot from the former Arsenal youngster from the resultant corner.
A flowing move from the U’s, involving Bean, Massey and Lee ended with the Hammers forward having a shot blocked.
That was Lee’s last involvement, as he was replaced by Jeffrey Monakana, who got straight into the action.
He got forward down the right and drilled in a low cross that found its way to Alex Gilbey twelve yards out.
Gilbey got a shot away but a deflection took all the pace off it and Weale easily collected.
There was then more injury problems, as David Wright pulled up with a hamstring problem and was replaced by Macauley Bonne.
It was the youngsters U’s debut, adding to the list of young players from the academy to make the step up.
Massey struck a low shot wide after cutting in from the left and then volleyed over as a free kick was cleared to him on the edge of the box.
There was no signs of the U’s settling for a point but that’s what they got, despite their decent second half showing.
A point was gained but it remains to be seen how costly the two injuries will be ahead of Saturday’s game against Peterborough United.