Originally Posted by Twyla
Vet check to begin with, full blood work done.
What does he do along with the sniff and growl? Is he in a forward motion, backs up, hackles? How long does it take and what occurs for him to settle?
It varies, but mostly he does get into confrontation mode, exactly as I have seen him do when barking at strangers he doesn't like or other dogs. He's usually quite extroverted and friendly, obeys all commands, plays and exercises a lot -the only way I can tell he's shifted into this 'mode' is when I notice his pupils dilate all of a sudden when sniffing me. If he's up on his hind legs playing with me, he grabs me and tries to draw me closer when the aggressive behaviour is triggered.
This stops if a) he gets distracted by someone or something else, or b) he calms down by himself. The latter left me clueless as one moment he's growling at me, the next he's wagging his tail and his usual self with me.
To add: he's never done this with either my wife or my parents.