I have a 6-month-old Australian Shepard who, in the last few weeks, has developed a fear of strangers, particularly men. She's a ranch dog with acres to roam, where workers come and go several times a week. This week she nipped a worker in the pants. She was barking angrily, and it didn't look anything like herding behavior. She is now an only dog, but from 8 weeks (when I got her) to 16 weeks, she had an older companion who died in April. This aggression never happened when the older one was alive. I've had a stranger feed her treats, and that seemed to work. She was a bit cautious but not under stress and the man was able to scratch her ears etc, and she was calm. There are other visitors, family, friends, men, and women where this doesn't happen. She becomes very excited to see someone she knows. She is well socialized with other dogs. I've done puppy classes and training with her. She is comfortable being out in the world and loves riding shotgun in a truck. If I can't correct this behavior, I may have to rehome her. I've had two other Aussies, and this was never a problem.
Is this behavior correctable?
Is it something she will outgrow, especially in light of now being an only dog?
Are there training techniques you would recommend?
Any help is greatly appreciated. Thank you in advance.