Slatmill vs motorised treadmill
Both move a belt under a running dog, but they work in opposite directions — and the difference decides which one suits a given dog.
The mechanical difference
A slatmill has no motor. The belt is a series of slats mounted on bearings, and it only moves because the dog pushes it backwards. A motorised treadmill sets a speed and the dog has to match it. Everything else follows from that.
Pacing
On a slatmill the dog chooses the pace and can stop simply by stopping. On a motorised belt the dog cannot, which is why motorised units need closer handling and a clear emergency stop. For a dog that has never used either, self-pacing is generally easier to introduce.
Resistance and conditioning
Because the dog is moving the belt itself, a slatmill adds resistance that a motorised belt does not. That makes it popular for conditioning work, and it also means sessions should start much shorter than they would on a motorised treadmill.
Noise, power and placement
No motor means no mains power and less noise, so a slatmill can go in a garage or outbuilding without wiring. It is usually heavier and takes more floor space than a folding motorised unit.
Which suits which dog
Motorised treadmills suit steady walking work, rehabilitation at a controlled speed, and smaller or older dogs. Slatmills suit fit, high-drive dogs doing conditioning work where the dog choosing its own gait is an advantage.