Staff

Meet our practitioners and read about their training, professional credentials and work experience.

  • Anne Breitinger, MD

    Dr. Anne Breitinger graduated from Northwestern University in Chicago with a bachelor’s degree in music prior to obtaining her medical degree from the University of Nebraska Medical Center. She came to Oregon to complete her internship and residency in Internal Medicine at Legacy Emanuel Hospital in Portland. After a brief time of working as an internist for Kaiser, she pursued her love for gastroenterology in Milwaukee, Wisconsin where she completed her fellowship at Aurora Sinai Medical Center. She has since practiced for several years in Southwestern Washington, as well as the Portland area prior to coming to Corvallis in the fall of 2018. She is board-certified in Internal Medicine and Gastroenterology and practices diagnostic and therapeutic endoscopy. In her free time, she enjoys hiking, trips to the beach, and watching her three girls play soccer.

  • Keith E. Harris, MD

    Dr. Harris attended Whittier College in California before earning his medical degree from the Howard University College of Medicine. He completed both his residency in internal medicine and his fellowship in gastroenterology at the Martin Luther King Jr. – Drew UCLA Medical Center. He is board-certified in gastroenterology and internal medicine. Dr. Harris specializes in both diagnostic and therapeutic endoscopy. He has worked as a hospitalist, urgent care physician, and internist. Dr. Harris joined Mid-Valley Gastroenterology in the fall of 2014 after having provided gastroenterology services in Roseburg, OR for several years. Outside of medicine, his interests include fishing, skiing, outdoor activities, and physical exercise.

  • Jonathan Hattenhauer, DO

    Dr. Jonathan Hattenhauer attended the University of Oregon where he received an undergraduate degree in Human Physiology before earning his medical degree from Western University of Health Sciences in Lebanon, Oregon. He then moved on to Manatee Memorial Hospital in Bradenton, Florida where he served as Chief Resident and completed his residency in internal medicine. In 2021, Dr. Hattenhauer completed his fellowship in gastroenterology at Hoboken University Medical Center-CarePoint Health. As a fellowship-trained gastroenterologist, he is skilled in evaluating, diagnosing, and managing GI conditions and is specialized in EGD, Colonoscopy, Push Enteroscopy, Pillcam, and PEG placement. Outside of medicine, he enjoys rooting for the Oregon Ducks, the Portland Timbers, and the Trailblazers. Dr. Hattenhauer is excited to return to the Willamette Valley to serve the community he came to love during his time in medical school.

  • Chad A. Morse, MD

    Dr. Morse received his medical degree from Oregon Health Sciences University in Portland and completed an internal medicine residency at the University of Arizona where he also served as Chief Resident. He went on to Brown University for his gastroenterology fellowship. He practiced in Boise, Idaho for 5 years before relocating to Corvallis in 2012 to be closer to his family. Dr. Morse is a board-certified gastroenterologist and member of the American Gastroenterology Association, College of Gastroenterology, Society for Gastrointestinal Endoscopy, and Crohn’s and Colitis Foundation of America. He performs a variety of therapeutic and diagnostic procedures and is dedicated to patient safety, comfort and satisfaction. He enjoys diverse hobbies including travel, skiing, tennis, diving, hiking, and boating.

  • Greg D. Schwartz, MD

    Dr. Schwartz completed his undergraduate degree at Wesleyan University in Connecticut before earning his medical degree from the Sackler School of Medicine at Tel Aviv University. He completed a residency in internal medicine at the Albert Einstein College of Medicine/Montefiore Medical Center, where he was named Outstanding House Officer. Dr. Schwartz completed his formal education with a fellowship in gastroenterology and hepatology at the University of Miami/Jackson Memorial Hospital and Center for Liver Diseases. He is board-certified in gastroenterology and internal medicine. Dr. Schwartz specializes in both diagnostic and therapeutic endoscopy. He has been published nationally for his research on capsule endoscopy and small bowel tumors and has a special interest in biliary endoscopy and inflammatory bowel disease. Dr. Schwartz has been practicing with Mid-Valley Gastroenterology since 2006. Outside of medicine, his interests include running, playing the drums, and spending time with his family. 'I am committed to providing the highest quality of care in both the endoscopic and clinical management of digestive disorders while maintaining the utmost respect and compassion for the patients of our community.'

  • Matthew M. Walton, MD

    Dr. Matthew Walton joined Mid-Valley Gastroenterology (previously Corvallis Gastroenterology) in the summer of 2009, after providing care in gastroenterology and hepatology at Dartmouth-Hitchcock Medical Center in New Hampshire. Dr. Walton earned his medical degree from the Medical University of South Carolina College of Medicine. He then completed an internship and residency in internal medicine, followed by a chief residency. Afterward, he remained at Dartmouth-Hitchcock Medical Center and completed a three-year fellowship in gastroenterology. During his chief residency and fellowship, Dr. Walton spent time volunteering at the Good Neighbor Clinic providing medical care and teaching medical students. As a faculty member at the Dartmouth Medical School, Dr. Walton was honored with the Outstanding Teaching Award in 2005. He is a member of both the American Society of Gastrointestinal Endoscopy and the American College of Gastroenterology. Dr. Walton’s primary areas of interest in gastroenterology include pancreatic and biliary disorders, endoscopic ultrasound, and ERCP. He is board-certified in gastroenterology and internal medicine. Dr. Walton was drawn to Corvallis by the vibrant college community, beautiful natural setting, and easy access to abundant outdoor activities. He is an avid mountain and road biking enthusiast and enjoys other outdoor recreation including snowboarding, cross-country skiing, and backpacking.

  • Dean Crowell, PA-C

    Certified Physician Assistant Dean Crowell has been practicing with Mid-Valley Gastroenterology since 2016. As a physician assistant, he works closely with the gastroenterologists and clinic staff to provide diagnostic, therapeutic, and preventative health care services. Dean sees patients in the office for evaluation, physical exam, treatment, education, and follow-up care.

    Prior to joining Mid-Valley Gastroenterology, Dean attended Emory University in Atlanta, Georgia where he received a Master’s of Medical Science in Physician Assistant Studies. Dean earned a Bachelor of Science in Exercise Science from Rutgers University in New Brunswick, New Jersey. He attended the University of North Carolina at Chapel Hill where he earned a Master’s in Exercise and Sports Science and Sports Medicine He is certified by the National Commission on Certification of Physician Assistants in addition to being certified by the National Athletic Trainers Board of Certification. Dean enjoys sports and spending time with family and friends.

  • Dena M. Hulting, PA-C

    Certified Physician Assistant Dena Hulting has been practicing with Mid-Valley Gastroenterology since 2007. As a PA, she works closely with the gastroenterologists and clinic staff to provide comprehensive patient care. She sees patients in the office for evaluation, physical exam, treatment, education, and follow-up care. Prior to joining Corvallis Gastroenterology, Dena worked at Oregon State University’s Student Health Services and with a multi-specialty group in Pennsylvania. She earned both a bachelor’s degree and Master's of Physician Assistant Studies from the Lock Haven University of Pennsylvania. She is certified by the National Commission on Certification of Physician Assistants and is a member of the American Academy of Physician Assistants. Her personal interests include spending time outdoors and reading.

  • Kristen H. Reeve, PA-C

    Certified Physician Assistant Kristen Reeve has been caring for patients in Corvallis since 2004. As a PA, she works closely with the gastroenterologists and clinic staff to provide patients with consultations on a multitude of gastroenterological issues. Prior to joining Mid-Valley Gastroenterology, Kristen practiced internal medicine at Oregon Health & Science University in Portland -- the same institution where she earned a Master’s of Physician Assistant Studies with high honors. She holds a bachelor’s degree from Oregon State University and is certified by the National Commission on Certification of Physician Assistants. She is also a member of the American Academy of Physician Assistants. Kristen is medically fluent in Spanish. In her free time, she enjoys tap dancing, outdoor recreation, travel, learning foreign languages, reading, and spending time with her husband and children.

  • Mary K. Reed, PA-C

    Mary joined Mid-Valley Gastroenterology after relocating from New England in 2015. Mary earned her undergraduate degree from Union College in Schenectady, New York. Thereafter, she gained years of patient care experience while working in physical therapy at a large hospital in Boston, Massachusetts. She attended Tufts University School of Medicine in Boston, where she earned her Masters of Medical Science in Physician Assistant Studies. She is a board-certified Physician Assistant through the National Commission on Certification of Physician Assistants. As a physician assistant, she works closely with the gastroenterologists and clinic staff to provide comprehensive care while focusing on patient satisfaction. Outside of medicine, her interests include volleyball, watersports, traveling, outdoor recreation, and spending time with her family, friends, and her dog.

  • Lisa R. Araneta, PA-C

    Certified Physician Assistant Lisa Araneta earned her bachelor’s degree from the University of South Florida prior to earning her master’s degree in 2005 from the University of Florida, College of Medicine. Lisa is a board-certified Physician Assistant through the National Commission on Certification of Physicians Assistants and practiced internal medicine in Florida. After coming to Oregon in 2010, she went to work for Samaritan Health Services where she spent over 5 years working in Nephrology and then transferred to Hematology/Oncology for almost 5 years. In her free time, Lisa enjoys the natural beauty of Oregon, hiking, biking, kayaking, and camping with friends.

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Hours of Operation

Our Regular Schedule

Monday:

8:00 am-4:30 pm

Tuesday:

8:00 am-4:30 pm

Wednesday:

8:00 am-4:30 pm

Thursday:

8:00 am-4:30 pm

Friday:

8:00 am-4:30 pm

Saturday:

Closed

Sunday:

Closed