Flashback? Dogs with Post Traumatic Stress Disorder (PTSD)?

Gracie had an odd episode the other night that I have to classify as a "flashback". I emailed the experienced folks at PSCR and started looking online.

Here is what happened - the other night, when I got home from work, I was petting her and our other dog in our kitchen, as we do every evening. Suddenly Gracie yelped very loudly and ran across the kitchen. She stopped for a moment, then yelped again and went racing upstairs and under our office desk.
It was almost as if something shot her to cause her to yelp, jump and then bolt. I can't imagine what triggered this. And she has never done this before.

She held her front paw up as if it was hurt and I was able to get her to come out and lifted her up onto the bed to inspect her paw. There wasn't anything stuck and I was able to move it about. I placed her back on the floor but she would not come back downstairs. I had to place her food in a different room than the kitchen. She did
venture into the kitchen when we sat down to eat our dinner. She also went for her nightly walk without a problem and doesn't have any trouble going up and down the stairs - so she seems fine to walk, her paw was not injured. I can't figure out what made her yelp and become so fearful. There were no different sounds or activities in the house to trigger this. It is almost as if she was having a flashback or imagining something happening to cause her pain. It made me very sad and it feels like all the progress she has made just vanished in a flash for no reason I can determine. What little joy she had left her.

The Wisconsin Puppy Mill site has an article about PTSD in puppy mill dogs.

I found this story on Best Friends, "They just want to be loved and want to love back" and wrote to Dr. Frank. I asked him, "Do you believe there is such a thing as PTSD in dogs or have you heard of dogs acting this way without provocation."

This was his reply:

"There is no question that dogs have their own form of PTSD.  We don't have a full understanding of it yet (which shouldn't surprise anyone, since we don't yet have a full understanding of the condition in human beings). The obvious difficulty for us is that we can't simply ask Gracie what was going on in her mind during her episode.  But what you describe is certainly consistent with a re-experiencing of psychological trauma.  The good news is that the vast majority of dogs showing these unusual behaviors do continue on with an upward progress in their recovery.  These end up being setbacks that can last days or even weeks, but, again, the overall trend is a positive one."

A couple days have passed and she is coming back to the level of interaction and happiness she had.  Everyone tells me to just accept her for where she is at .  I can do that and it helps to know that although worrisome, it can be overcome with time and patience.