The young Irish defender who has been linked with a summer move to rivals Partick Thistle smashed home the equaliser with only 14 minutes to go.
In a dull game that never really came to life, Dumbarton grabbed the lead on 14 minutes but with a large slice of help from the Ayr defence.
Home full-back Michael Dunlop lost out to Ryan Borris on the touchline, when the ball was played inside John Gemmell linked up a shot at goal. Keeper Ludovic Roy appeared to have it well covered until it hit the outstretched leg of defender Barry McLaughlin and was diverted for a cruel own goal.
Dumbarton came close to adding a second soon after but John Dillon's free-kick from 22 yards was acrobatically held underneath the bar by the diving Roy.
Ayr had the ball in the net on the stroke of half time when Andrew Reid fired home a cut back from Stuart McGrady but the linesman flagged for offside.
Ayr started the second half brightly and Reed and Paddy Connolly both had good efforts.
United's pressure paid off on 76 minutes when substitute Richard Buckley sent over a cross which was headed back by Craig Conway and slammed home by the inrushing Mark Smyth. Both sides could have won it in an entertaining finale.
James McKinstry fired just wide for Dunbarton while at the other end Paddy Connolly was only inches wide after being sent clear with a pass from Mark Smyth.