It is entirely possible that your pet has suffered some cerebral vascular incident, better known as stroke. Certainly meningitis, acute blindness and brain tumor are also possibilities. These would not show up on blood results necessarily.
MRI or CAT scans usually diagnosis the problem, however a spinal tap may also be necessary to give a complete answer. If this is a stroke, then rehabilitation can take a long time to resolve the symptoms, and may not improve beyond a certain point.
Treatment depends on the cause. Ask your veterinarian for a referral to a teaching hospital to further address this problem.
Dr. Van Lienden
Dr. Raymond Van Lienden DVM
The Animal Clinic of Clifton
12702 Chapel Road, Clifton
Virginia, U.S.A. 20124