I have a 9 month old beagle mix who recently discovered the wonderful game of playing fetch. Initially, I was thrilled to have another exercise outlet.
However, she has increasingly become more possessive of tennis balls when we go to the dog park. She "growls" (or in her case, high-pitch "yells" with teeth showing) and moves any dog away from any tennis ball she deems "hers." She gets pretty angry when she's in the middle of a game of fetch, drops it for me, and another dog snatches it before I can. (We are still working on drop-it INTO my hand.) Unfortunately this is not the only scenario that she guards though. She likes to run under the benches with a ball/frisbee and then proceeds to scare away any dog that tries to come near her.
This behavior has started recently, like within the past month or so. We have been going to the dog park since she was 4 months old. I would really hate to have to stop going because when she's not guarding, she's playing nicely and having fun.
However, she has ended up getting into with a couple other dogs. Luckily, some of the "regulars" who I know personally now. She seems to now back off for these certain dogs even on different trips to the park that have happened after the trips when the "fights" happened.
We have tried leaving the park after she becomes "possessive," but I don't think she understands the association between: being mean = leave park.
I'm not sure what the next step would be in nixing this behavior. Is she just being a teenager? Do I need to go to a professional or is this something I can fix along with some of our friends with dogs?