Danny Williams headed Wrexham into the lead from a Darren Ferguson corner early in the second half and it looked as if the home side would take the points.
But Macclesfield boss Horton had other ideas and changed tactics to get back into the game. He threw on Aaron Russell with Martin Bullock and Kevin Townson to go three up front, instead of persevering with a loan striker and five across midfield.
It paid off within two minutes as substitute Russell burst through the middle, shook off a tackle from Paul Warhurst and hammered a crisp shot past teenage goalkeeper Michael Jones.
It was bad luck on the 17-year-old, who had come on in place of first-choice stopper Michael Ingham, after he was struck down by a groin injury midway through the first half.
Wrexham had a purple patch after half-time and were unfortunate not to get a quick goal. Ferguson made a fine opening for Jonathan Walters, but his stinging shot was kept out by Alan Fettis' good save.
Mark Jones then ran through from midfield and let loose with a 20-yard drive that flew inches over the bar.
Then Wrexham won a free-kick on the edge of the area which Ferguson nudged a couple of yards for Dean Bennett to try a shot which also cleared the bar.
Wrexham had to soak up early pressure before Walters broke off upfield to set up Jones for a shot which flew just wide.
Jones fired a long range drive straight at the goalkeeper and Ferguson had his shot deflected for a corner. Another shot from Williams brought a fine save from Fettis who saw it late in a crowded goalmouth.
Macclesfield had another narrow escape when Walters nearly pounced on a weak back pass from David Morley who was grateful to see Fettis save the situation, racing out to clear.