Re: Times changing regarding dogs. This is actually a truth, though I don’t know enough to say what the situation was with dogs in general in the times of the gemoro. Has anyone ever heard of a woman miscarrying from seeing a dog these days? Things have probably changed somewhat.
Dogs are related to wolves. They are not naturally tame animals. They were very useful because of their ferociousness (that’s what a watchdog is) and because they had the capacity for loyalty to their owners. You would not generally want to be near a dog any more than you would a wolf.
However, in the present day, dogs are domesticated animals and have been already for generations. We train our dogs to be friendly, not ferocious. That is why most watchdogs nowadays are useless – if you throw them a treat they will roll over and lick your hand.
Clearly, dogs are not what they used to be (though they are still at root potentially dangerous animals and we hear stories from time to time). Whether that means that the halacha regarding owning them is different now I certainly cannot say. However, what I have seen only speaks about a “bad dog”. I have never seen a halacha that says one cannot have ANY dog. If the metzius today is that most dogs are not wild then that means the halacha only applies to a minority of dogs.