Sneezy, your story is only the second time I've heard of something like this.
Many years ago, I worked with a young woman who looked like Barbie & had a mind like a steel trap!
She was generally aloof, but one day she shared this with "us girls":
She had been brought up by...grandparents?...some family members, who refused to let her have a pet.
During her teens, she started dreaming of a small black dog, something like a Scottie, & she *knew* that that was her dog.
Years went by, she grew up, got her own apartment, never got around to looking for a pet.
On the way to work one rainy morning, she saw a small muddy white dog running scared along the freeway.
She stopped, opened the door...& the dog hopped in, sat down, & "smiled" at her.
She drove to a nearby vet & left the dog to be cleaned up & cared for until she got off work.
She said her mind kind of "itched" that day, trying to figure out why the dog seemed so familiar.
When the vet tech brought out the now shampooed & brushed dog, she realized that this was the "black dog" in her dreams.
Laughing, she said, "Some people dream in photographs. Trust me to dream in negatives."
She & the dog spent nearly 16 years together.