I agree that the owners are the problem, not the dogs. There's a thread in commuting right now where folks are arguing about the best ways to deal with dogs.
Research has shown that "chase-proneness seems to be influenced by the dog's interest in playing with objects" and not aggressiveness.
The bottom line is that unless you're encased in steel, you're going to encounter dogs whether you're cycling or not, a minority of which will pose an actual threat (ask your mailman or the guy you see out running all the time). Since you are moving fast, you are going to attract more dogs chasing you than a slow moving person would, but that doesn't mean these dogs want to attack you, in fact research indicates the opposite. Some dogs are aggressive and will bite you, but you're only going to encourage them if you keep running. You are more likely to get chased, but you're no more likely to get bitten than anyone else who is walking/running by (those dogs are a serious problem for everyone, not just you).