Last year (I think) Ginger had a bout of vestibular issues with no apparent cause. One ear was a tiny bit waxy, but that's it. They assumed she perhaps had a brain tumor, as it didn't fit the normal vestibular issues. But, she recovered fine with no lasting effects. It was alarming, though, to leave a normal dog in the morning and come home to a dog who could barely stand, was all tilted to the side and whose eyes flicked constantly.