Dogs can freak out over odd things. The dress might have a strong enough pattern to confuse him, change your body shape in his eyes, or it could have just been coincidence if it was the first dress you tried on.
Chester went nuts barking at my neighbors yesterday (and he nearly never barks and is about the most bombproof dog around) because the father was swinging his toddler son around by the arms (the spinning type game) and I think Chester thought he was hurting him. Once we walked by a house we'd walked by a 100 times and they had PAINTED bears on the garage and Chester growled at the bears
Luna went nutty the first time she saw someone holding an umbrella and went nutty barking at my aunt wearing Christmas reindeer antlers (the little decorative headband antlers). Yesterday she barked a bit at an angel statue in a yard.
Chester went nuts barking at my neighbors yesterday (and he nearly never barks and is about the most bombproof dog around) because the father was swinging his toddler son around by the arms (the spinning type game) and I think Chester thought he was hurting him. Once we walked by a house we'd walked by a 100 times and they had PAINTED bears on the garage and Chester growled at the bears
Luna went nutty the first time she saw someone holding an umbrella and went nutty barking at my aunt wearing Christmas reindeer antlers (the little decorative headband antlers). Yesterday she barked a bit at an angel statue in a yard.