It's *resource guarding*and it isn't unusual.Don't give her the opportunity to do it.You've seen for yourself how it begins to escalate and becomes habitual.I would put her in a sit/stay behind me when another dog approaches and she rushes over.I would not interact with the other dogs and not allow the opportunity to become possessive over treats and toys.This may be a problem unless the other folks will get on board with you.You say you only go to the beach when it's not crowded?Ideally play dates with known dogs and owners are best.
My hubby's dog is a terrible resource guarder
We did not let her practice the behavior and always have her wait her turn when treats are dispensed.Always!!You can see it in her eyes that she feels as "queen of the land" her desires should come first
But it's just not worth the effort anymore and she is habituated to standing down and always acknowledged with a "Good Girl!" at the very least.Compliance has become rewarding.
Samson Blk/Slvr GSD. RN
Misty Husky Mix
Z-Z Terrier/potato mix
Devo Yorkie Mix at the bridge
Dakota Wht GSD at the bridge