I have a 3-1/2 yr old JRT/Brittany mix (female) who hates skateboarders and motorcyclists. Whenever we see one on a walk she goes crazy, barking and lunging. I'm worried about this because we walk on sidewalks by busy streets, and she could lunge into the street after one. I'm not sure if it's a prey-drive thing (she also chases squirrels, birds, cats, and any other assorted small mammals we see) or if she's scared of them. Also, as the target of her barking is traveling away from us, her tail starts to wag like it's a big game. Any suggestions? I have tried distracting her with treats but it only works if the target is pretty far away. Otherwise, she is not that food- or toy-motivated. Any suggestions?
Oh, I forgot to mention that she reacts the same way to people on roller skates, scooters, and (strangely) to trucks that have noisy cargoes - things that clank and make noise as they go by. She is also scared of loud noises like thunder and fireworks.
We have only had her for about 6 months (since December). Could something have happened in her former life that would leave her scared of these radically different (at least to me) things? If it helps, her shelter papers said she was an outside dog, and not housetrained (but thankfully the foster family started her on that).


