The City must adopt a bylaw that bans the keeping of dogs 24/7 in a yard, or as in Lions Bay, the keeping of dogs unattended in a yard, and the bylaw also must require owners of dogs large enough or powerful enough to do severe damage (of any breed), to socialize them (testing can be done) and train them (training certificates required).
If the City does the humane thing for dogs, then the safety of its citizens will follow.
The SPCA must use the Prevention of Cruelty to Animals Act to prevent the cruelty of dogs kept in isolation, if these owners start to isolate their dogs inside.
If the owners of dogs who do not have any sympathy for a dog's emotional needs finally realize that they must keep the dog inside, instead of outside like livestock, most will dump the dog at a pound or an SPCA. (That's when the rescue network has to throw itself into trying to save these dogs from death or being resold to other abusive owners.)