Given that I've stirred up a bit of debate (sorry), I thought I should share my views about the towpath, the aqueduct and dogs. To put things in context, I ride it every day from Meggetland to beyond the bypass. I've notched up three years and 7,000 miles on it so far.
Key thing for me, as a regular user, is that it's a narrow shared space with a water hazard on one side. Everyone on it has to look out for themselves and to think about the impact of their actions on everyone else. If what I want to do causes avoidable fear or inconvenience to another towpath user, I should stop it. It doesn't matter if 'I' am a cyclist, or a pedestrian (with or without a dog)
Under 'causing fear or avoidable inconvenience', I include: going too fast for the situation on a bike, not paying attention to what other users are doing, not wearing something reflective when it's dark, not warning pedestrians when approaching from behind on a bike, not keeping a dog under close control, not keeping children under close control...
Interestingly, this philosophy still applies when I cross the aqueduct. When I'm travelling at key commuter times, I would actually cause more avoidable inconvenience to the stream of bike commuters if I walked across. A pushed bike is wider than a ridden one, and it slows everyone down. At those times, I ride across. When I'm going to the allotment on a sunny Sunday afternoon, I am unlikely to ride across the aqueduct because the traffic is then families and people out for a stroll. Riding across would cause them avoidable fear and inconvenience, and I shouldn't do it.
There was no drama with the white dog yesterday. I was never at any risk of hitting it. If you listen to the bike noises you'll hear me feather the brakes as soon as it appeared, change gear and then brake to a halt as soon as it was clear that it was totally out of control. In my view having to stop was an 'avoidable inconvenience' and something its owner should try to avoid causing to other users of the shared path.
I try my best to be a courteous user of the path by trying to avoid frightening or avoidably inconveniencing the people I'm sharing it with. All I can hope is that all the other users do the same.