Some background on the dog first, we adopted a 3 year old Chow mix in february and has been a great dog apart from some lack of training (no training in those 3 years) and is very loving and always wants attention and to be petted.  He also gets walks fairly often and he likes being outside.  He has had some trouble with other dogs but he mostly ignores them now.  These past few weeks he has been acting strangely at night however.  He used to only sleep in his crate, even when we let him have freedom to choose where he sleeps, but now he sleeps either behind the door of my sisters room or behind the couch.  Then when you touched the door or couch in the slightest he would start to growl and show teeth.  I have been putting him in his crate when he would do that.   Today however, while watching Tv he randomly gets out from behind the couch and starts snarling and being aggressive towards me and my sister.  I got up and grabbed by the collar and he whipped his head around and clipped me with his fang, not trying to bite but more of a head motion deal.  After that he tried to go into my parents room and ran to grab a treat to attempt to calm him down (I knew i shouldnt have).  I then put him in his crate and he laid down and slept like normal.  I have no idea what triggers this behavior and have no idea what to do when he is that state of mind.  Any advice would be nice.
user
My dog is getting aggressive at night and I don't know how to handle it.
assistant
Some background on the dog first, we adopted a 3 year old Chow mix in february and has been a great dog apart from some lack of training (no training in those 3 years) and is very loving and always wants attention and to be petted.  He also gets walks fairly often and he likes being outside.  He has had some trouble with other dogs but he mostly ignores them now.  These past few weeks he has been acting strangely at night however.  He used to only sleep in his crate, even when we let him have freedom to choose where he sleeps, but now he sleeps either behind the door of my sisters room or behind the couch.  Then when you touched the door or couch in the slightest he would start to growl and show teeth.  I have been putting him in his crate when he would do that.   Today however, while watching Tv he randomly gets out from behind the couch and starts snarling and being aggressive towards me and my sister.  I got up and grabbed by the collar and he whipped his head around and clipped me with his fang, not trying to bite but more of a head motion deal.  After that he tried to go into my parents room and ran to grab a treat to attempt to calm him down (I knew i shouldnt have).  I then put him in his crate and he laid down and slept like normal.  I have no idea what triggers this behavior and have no idea what to do when he is that state of mind.  Any advice would be nice.
user
Dog randomly gets aggressive at night, what should i do?
assistant