They had this on the news this morning. Kinda looked to me like the dog was dreaming it was BEING chased, not chasing something, just based on how he lifted his head and snapped as if something was behind him.

I've seen several dog seizures at work, and a seizure on my RB cat Dusty, and this video didn't look like any of them. Just looked like a dog having a very, very bad nightmare.

Poor baby, glad he didn't go running down any stairs or anything. It was funny until he started snapping then actually up and running.