Lyme disease can cross the blood brain barrier and cause disease in
the brain. This is documented in
humans but not yet in
dogs, but I believe it can occur in dogs also. That may or may not be the cause of seizures in your dog. Seizures in dogs can occur secondary to trauma, metabolic disease, lesions or tumors in the brain, from a variety of infectious causes, toxins, and, ideopathic causes. Ideopathic means of unknown cause.