1. Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas.
2. Department of Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas.
3. Department of Physical Therapy and Rehabilitation Science, University of California–San Francisco, San Francisco, California.
4. Department of Neurological Surgery, University of California–San Francisco, San Francisco, California.