Our dog (a beagle/small shepherd mix) is a humane society adoptee. We've had her for nearly 8 years (she'll be 10 in 09/12). She has her quirks, mainly some fear (aggressive if cornered or on leash) of men, particularly bald men. Yelling and anything that vaguely looks like a weapon also freak her out. We figure that something must have happened to her before she was left at the HS. She's never been scared of thunderstorms, fireworks, etc.
She's getting older; this past winter she acted as if she were a little stiff getting up in the mornings, and her back end seems to slip on the hardwood floors nowadays (to me, it looks like she "shuffles" her back paws). This past spring, she had a spate of episodes that my sister commented as sounding like "sundowning". She would pace, pace, pace during the wee hours of the morning. Sometimes she would settle after going outside, sometimes not. Thankfully that only happened for a couple of weeks (or maybe now we sleep through it).
In the past month, she's developed some new, strange behaviors that have us puzzled. She started acting like she forgot how to turn around in the hallway. Instead, we hear her "shuffling", and she BACKS around the corner in the hallway before finally turning around. Most recently, she's become fearful of coming around the corner of the hallway, period (just the one hallway into our living room). She stops at the corner, peering around at us. She'll back away, make several more approaches, try to come down the other side, back away. Then she'll make a sudden scoot/dash/slippy scramble the 3 feet between the corner and the rug in the living room. We haven't changed furniture, so we're really scratching our heads about why she's suddenly doing this. Her vet appointment will be in the next month, so we'll discuss it with him too, but I'm curious as to whether anyone has any experience with this? I've wondered if this is early doggie dementia.