This is more of some input/ideas, feel free not to answer! Someone might have said this already, but if they haven't I am saying it now: I read your 'strangest experience' answer (the spectral dog and then the physical dog) and it really struck me! Firstly, spectral black dogs are such bad omens! To be pursued by one is terribly awful luck. To be followed or have your path blocked by a physical black dog is a very good omen, however and so I think that is what happened to you! It shooed the bad.
Going to post this because that’s actually a pretty interesting idea, I hadn’t thought about it like that!
Having said that, where I grew up has a very famous black dog legend. I grew up in the countryside of East Anglia in England, the counties of which have been known for centuries to be the home of a spectral black dog known as the Black Shuck. A lot of these reports have the dog as a bad omen or even a hellhound, however there are also legends suggesting it warns of bad events and is even a protector of lone travellers. I thought that was pretty interesting, given my tendency to wander, and the fact I dreamt of the dog only before tragic or dangerous events occurred.
I’m still not sure if the physical dog was a representation or something completely different, but this theory is definitely worth keeping in mind. It’s always been something I’ve thought about a lot.