He generally goes crazy, but with tail happily wagging at body level, but hackles raised. This only began recently, and otherwise he is quite well behaved. I am expecting a baby in a few months and I think it may have something to do with his instinct to protect "mom", as when we are home, he will lie next to me with his head on my tummy.
11 month old purebred lab, ridiculously intelligent, learns everything you try to teach him. Gets along well with my parents dogs (2 English setters and a very obese border collie) as well as his housemate, a smaller pit mix. I honestly cannot tell if it's protective instinct or excitement.