J. Frederick Shield, MD, is a specialist in internal medicine and has been practicing at Cedarwood Internal Medicine in Sonora for many years. He previously practiced in Boston for eight years after completing medical school and residency at Loma Linda University. As an internist, Dr. Shield specializes in treating both simple and complex patients in their adolescence through adulthood. Dr. Shield has a special interest in keeping adults healthy and active using preventive patient education and medical treatments when necessary. Asthma, COPD, sleep apnea and other breathing issues are of particular interest.