Yeah you dang right it is a hard call. I had a Beagle/springer awhile ago and it was the most mild mannered, lick anyone to death dog! One day my son was between my legs standing and the dog came up beside me and all of the sudden he showed his teeth and started growling. Out of pure reaction the dog did about 2 flips before it hit the wall. Not that it was the right thing to do but it was a snap solution to the problem. needless to say that dog never showed his teeth to my son ever again and I am soooo glad I didn’t get rid of him! I read somewhere once that when a dog and child are at the same eye level that it sometimes feels threatened. I guess it is if you feel the dog would actually follow throught with it(aggressive dog), if so I say yes get rid of the dog. If you decide to keep the dog, maybe getting your son more acclimated to the dog(playing fetch,feeding,petting) would help their relationship, and maybe the dog won’t feel your son as a threat. I’m no dog expert but once it happened with my dog, he knew he crossed the line and as my son grew older never once did it happen again. Do you think your dog is possible of doing it?