Slough started strongly and Luke Knight went close from distance in the opening minute, his shot from 25 yards clearing the bar, before Scott Harris saw an attempt saved by Alan Walker-Harris in the Dorchester goal, with Knight tackled before he could pounce on the rebound.
Soon after, Adrian Sear let fly from outside the box, and his shot hit Scott Harris, which made for an awkward save for Walker-Harris, but he did well to keep the ball out.
Knight went closer still as he volleyed against a post, before the home side took the lead on 23 minutes, top scorer Eddie Smith lashing in a loose ball from 15 yards after Connor Doe blocked a shot from Knight.
Dorchester rallied and equalised, as Slough went off the boil. Sam Lanahan got in front of Jake Somerville after Robbie Matthews flicked on a free kick, and the midfielder headed over the Slough keeper, capitalising on hesitant defending from the hosts.
Neither side added another goal in the remainder of the first half, with the balance of play swinging towards the visitors.
The second half was a fairly even contest with clear chances at a premium and both defences clearing their lines well. Dorchester missed a couple of half chances early on, with Jack Odam heading over the bar and Connor Doe's long range strike deflected up and into Somerville's arms.
Somerville pushed a strike from Lanahan behind after a strong run, whilst for Slough, Harris headed over a cross from Jake Parsons, before the increasingly influential midfielder was himself thwarted by Walker-Harris, the keeper turning behind a stinging shot.
Play moved from end to end in the closing stages, and after a spell of possession and pressure, Slough found what proved to be the winning goal. Adrian Sear's exquisite through ball split the Dorchester defence, and substitute Dyer ran on to it and fired past Walker-Harris.
Jake Parsons was denied a goal by another good block from Walker-Harris, but the Rebels had done enough to continue their run of good results following victory at St Neots and a hard-fought draw at Frome, and condemn Dorchester to a fourth straight league defeat.
Dorchester Town Line up
Alan Walker-Harris, Connor Doe (Ryan Murray), Matt Oldring, James Gleeson, Robbie Matthews, Chris Dillon, Nick Crittenden (c) (Alex Godfrey), Sam Lanahan, Jack Odam, Dan Smith, Mason Walsh (Kieran Parrett). Subs not used: Tony Rolls, Shane Murphy.