For information about vestibular syndrome, here is an excellent link:

Vestibular Disease in Dogs and Cats
Wendy Brooks, DVM, DABVP
Date Published: 01/01/2001
Date Reviewed/Revised: 03/31/2011

Take home points:
1) usually occurs in old dogs/cats
2) most common in spring and fall, but, can occur anytime
3) no test available; usually a diagnosis of exclusion, ie. rule out other problems
4) no treatment, except anti-nausea, anti-vertigo meds
5) usually occurs once, but, in a few pets can reoccur
6) symptoms can resolve in as short as a few hours, to several months. Typical is about 2-3 weeks.
7) some dogs are left w/ minor-moderate balance issues, and/or head tilt
8) unpleasant (dog feels dizzy and urpy) but, not painful
9) often mis-diagnosed as a “stroke”

From an owner: I’ve had 2 dogs with “old dog” or geriatric vestibular disease. The research I found said that it will resolve itself on its own, usually in a couple of weeks. It lasted longer than that with my dogs. The first was a 13 year old Doberman. I had to put a harness on her to hold her up so she wouldn’t fall over. I’d say it was closer to 2 months before she was able to walk on her own. The head tilt can be a permanent side effect, which happened with my 2nd dog, a miniature dachshund. Didn’t sound like there’s any really great medication for it. My Dobe had problems with nausea, which would be understandable while feeling dizzy. You may also notice your dog has a rapid horizontal eye movement (just slight movement). I fed my dog Hills I/D watered down while she had it. My Doberman was in an obedience trial about 3-4 months after this happened. She also had a reoccurrence of vestibular disease about 6 months later but it wasn’t as extreme. My vet put her on prednisone but I don’t think that really helped.”

From another owner (non ME dog): “I had a dog (not ME) who had geriatric vestibular syndrome. She couldn’t stand or walk at all, head tilt was extreme. It took two to three weeks for improvement to start and, in the meantime, treated her with sub! fluids, anti-nausea medication, and hand feeding small amounts of anything I could get down her (some days that was nothing, others it might have been a bit or two of a hot dog or some other tasty morsel). She did recover fully, but it very hard work in the meantime.”