I can confirm it was the familiar that caused the dog attack. (My player character is a ranger and had a raven with him) Without raven, everything was normal. Thanks for the hint !
Sooooo.... Larian forces me to choose to kill either my dog or my raven.
When we're in the camp and I summon a familiar there, the dog doesn't mind.
Oh yes, I tried one more thing : Send Shadowheart alone to the camp to pet the dog and make him feel at ease, and then follow with the rest of the party, but the dog still attacked.
