Basenji is waking up screaming in the middle of the night?

[anp1107]

I got him at 10 weeks old from a local shelter. I was told that there was no abuse or neglect from the previous owners. They were an elderly couple that didn't have time to care for 4 puppies. He is 4 now and I'm not sure what he is mixed with. For the last 6 months he randomly wakes up screaming in the middle of the night. It is normally between midnight and 3:00 a.m. When I mean scream it is not some light yelp. This is a full out terrorizing almost human noise. The first time it happened I thought my neighbor was being attacked. It happened 6 times in the month of June and then stopped. The next time it happened was Thanksgiving weekend and then again last night. One night he woke up twice. It's not every night. It is completely random. He does not shake, convulse, or have his eyes shut when it's happening. He just sits or lays there. Most of the time he looks scared and aware that it is going on. One time I heard him yelp and I woke up to him jumping into bed with me and he started screaming. It takes normally 30 seconds to a minute to calm him down. He then wants to cuddle under the blanket. He sleeps on a dog pillow and blankets on the floor next to my bed every night.

I took him to the vet and he is completely baffled about what could be going on. They did bloodwork and xrays. He ruled out epilepsy. He tells me to just keep a log of when it happens. We have not changed his food. He hasn't experienced any new changes recently like a move, or new family member so I'm not sure what could be stressing him out. He does not do it when he naps. He could nap for hours on the couch and never make a peep.

Has anyone ever experienced anything like this? Or have advice on what could be wrong and how to help him? Could this be night terrors?