Diane, what an interesting statement about strange behavior in animals!  My dog has been doing the same things, and I was about ready to take him to a doggie psychiatrist! 

 

He loves to go for his evening walks around the neighborhood, straining at the leash all the way.  Then, about 2 months ago, he'd be trotting along and suddenly stop in his tracks, looking this way and that, sniffing the air, listening for something, and refusing to MOVE.  I couldn't DRAG him one more step forward.  So, I'd turn him around to go home.  Most times, he would practically RUN home with his tail down.  Sometimes he wouldn't move AT ALL, and I've had to CARRY him home.  (He's 22 lbs.)  This went on for 2 months, then suddenly it stopped, and he's OK on his walks again, except for once in a while he will still "freak out" somewhere on this walk.  It appears that he senses something is very, very wrong in the neighborhood, and he frankly looks scared.  He can hear and smell things way beyond the human range of sensitivity.

 

The other thing he's doing is this weird growling all night long.  I can't make him stop.  He lets out a bark once in a while, and he's facing no particular direction.  It's not like it's a cat coming over the southwest fence.  He just sits in the middle of the living room and growls.  Or if he's on our bed (he sleeps with us), he has disrupted many hours of sleep on many evenings, and created 2 furious dog-owners.

 

It's reassuring to know that there might be an explanation for this behavior, even though it's a sinister explanation.