I've found that dogs are the biggest hassle on trails. Part of my commute to work is a favoured spot for all the local dog walkers to give "Spot" a bit of exercise. I nearly got taken out the other day by a dog that had decided to carry a branch (I'm serious - this was no mere stick) with it on its adventures. I've discovered that going past them without causing a fuss (although slowing down quite a bit) is the best way to keep out of their way. But this one heard me at the last minute and came to investigate what I was, branch and all! Made for an interesting skid, as it had been raining and the tarmac was wet - emerged unscathed though which was a relief.