It is great fun David and I've not felt this fit for a long time. Evidently, push scootering burns 30% more energy than riding a conventional bike. It's a junk, cheapo fleabay kick scooter that I've thrashed the life out of in a couple of months, doing over 360 km (224 miles) so far. I might upgrade to a proper dog scooter soon. I don't see myself giving this up now that I've got into it.
You should get your pack of Rotties working too. They'd love it.
Here's the max speed so far (27 kph - 17 mph). The average 'walking pace' for us is around 10 to 14 kph (6.2 to 8.7 mph). He could go faster I'm sure. I just won't let him until I get some disc brakes. Freight trains don't stop on a dime.