Regional Institute for Veterinary Emergencies & Referrals

2132 Amnicola Hwy Chattanooga, TN 37406

Phone : 423-698-4612

Fax : 423-622-8145

Our Veterinarians

Dr. Sallye Gregg, DVM, Residency Trained; Medical Director

Our Veterinarians

Sallye Gregg, DVM, graduated in 1980 with a BS in Animal Science from the University of Tennessee Knoxville. She continued at The University of Tennessee College of Veterinary Medicine where she received her Doctor of Veterinary Medicine in 1983. Dr. Gregg spent the next seventeen years working and managing a full service private practice in Cleveland, Tn. In 2000 she moved with her family to Charleston, South Carolina where she served as the Medical Director for the Greater Charleston Emergency Clinic, and Mt. Pleasant Emergency Clinic. From 2002-2006 she completed a residency in Emergency and Critical Care while serving as the Director of the Emergency Department at North Carolina State University College of Veterinary Medicine. Dr. Gregg is currently serving as the Hospital Director of the Regional Institute for Veterinary Emergencies & Referrals (RIVER). Dr. Gregg lives in Ooltewah with her husband Steve, and has two sons Dustin and Will. When she's not at the hospital, you can find her riding her Harley-Davidson, reading, or doing cross-stitch.

Mark Bohling, DVM, PhD, DACVS, Chief of Surgery

Our Veterinarians

Dr. Bohling is a 1986 graduate of the School of Veterinary Medicine, University of California, Davis. After working as a food animal veterinarian for six years, he began working in small animal general and emergency practice in 1992. In 2004 he completed residency training in small animal surgery at Auburn University, and has been board certified since 2006. In 2007 he finished a PhD, also at Auburn, where his dissertation work focused on comparative wound healing, specifically regarding how wound healing in cats differs from wound healing in dogs. From 2005 to 2012 he served on the faculty at the University of Tennessee College of Veterinary Medicine. Dr. Bohling joined the Surgery Department at RIVER in November 2013 as a general surgeon. He considers himself a general veterinary surgeon, ready to accept just about any surgical challenge that comes to RIVER. Within the broad field of general surgery he maintains special interests in wound management, reconstructive and oncologic surgery, fracture repair, and surgery of exotic species.

DJ Krahwinkel


Dr. Krahwinkel completed his undergraduate studies at The University of Kentucky (1960) and Western Kentucky University (1961-62). He attended Auburn University College of Veterinary Medicine, where he graduated Valedictorian of his class in 1966. He continued his education at Michigan State University with a Master’s Degree in 1973. He is triple boarded in small animal Emergency and Critical Care, Anesthesia, and Surgery.

Dr. Krahwinkle taught at Michigan State University College of Veterinary Medicine as an Assistant Professor of Anesthesiology and Surgery from 1969-75. He then taught at The University of Tennessee College of Veterinary Medicine as a Professor and Head of Small Animal Clinical Sciences from 1975-2002 and a Professor of Surgery from 2002-present. He is a diplomate of the American College of Veterinary Surgeons, the American College of Veterinary Anesthesiologists, and a diplomate of the American College of Veterinary Emergency and Critical Care. He served as the President of the Tennessee Veterinary Medical Association from 1987-88, the President of the American Association of Veterinary Clinicians in 1998, and was a member of the AVMA House of Delegates from 1999-2003. He visits R.I.V.E.R. every other Thursday to perform soft tissue surgeries.

P.K. Hendrix, DVM, PhD, DACVA

Our Veterinarians

Dr. Hendrix is a Louisiana native. She graduated from the Louisiana State University School of Veterinary Medicine and practiced for a short time in a mixed animal practice in south Louisiana. She completed her anesthesiology residency and PhD from the University of Minnesota, remaining on faculty at the University of Minnesota for a total of 12 yrs. In 2001, she and her husband, Mitch, moved to Mississippi where she was a faculty member at the Mississippi State College of Veterinary Medicine until 2008, when they relocated to the Nashville, TN, area. In Nashville, she was a clinician at Nashville Veterinary Specialists until December 2013, when she and Mitch decided to move to the beautiful Chattanooga area where she is now a member of the RIVER team!


Our Veterinarians

Dr. Crowe received his DVM in 1972 at Iowa State University. He completed a rotating internship in 1973 at Colorado State University, followed by a 3-year surgical residency at The Ohio State University in 1976. He received board certification in surgery in 1980. He became a founding member of the American College of Veterinary Emergency and Critical Care in 1989. Dr. Crowe is an Emeritus Diplomate of the American College of Veterinary Surgeons and is a Charter Diplomate of the American College of Veterinary Emergency and Critical Care. He was the first President of the VECC and last President of VCCS and instrumental in bringing emergency care and critical care into one organization.

A founder of ACVEC, he received the VECCS Zaslow Award for his pioneering, teaching, leadership and innovation in veterinary emergency and critical care in 2004, and was awarded Fellow status in the American College of Critical Care Medicine in 2007. Dr. Crowe is an active certified firefighter and licensed medic. He is active on the Program Committee of the Society of Critical Care Medicine, and was recently awarded a President’s Citation for significant contributions in critical care in 2014. Dr. Crowe is a member of the American College of Hyperbaric Medicine, and has published more than 500 refereed and non-refereed articles and proceedings and has given over 1000 invited lectures worldwide.

Dr. Crowe is a father of 2 and grandfather of 6. He has been married to his best friend, Deb, for 44 years. His hobbies include playing the guitar and harmonica for his church’s Praise Team and for Kairos Prison Ministries.

Cheryl Braswell, DVM, DACVECC, CHT-V, Chief of Emergency and Critical Care

Cheryl Braswell

Dr. Braswell has been practicing veterinary medicine for 36 years, graduating from the University of Georgia in 1979. She originally started her career as an associate small animal general practitioner. After 5 years she established her own business and continued in general practice for the next 17 years. Having retired from general practice in 2005, she pursued a residency in small animal emergency and critical care. In addition to her diplomate status in the American College of Veterinary Emergency and Critical Care (2012), Dr. Braswell is also a Certified Veterinary Hyperbaric Technologist (2013) and is currently seeking certification in veterinary pain management.

Dr. Braswell served as a Clinical Associate Professor for the College of Veterinary Medicine at Western University in Pomona, California before moving back to the Tennessee area in 2015. She especially enjoys teaching in the clinical setting, routinely supervising externs and interns. Most recently, Dr. Braswell has developed a sincere passion for care of veterinary patients with life-limiting diagnoses. She believes there is a place for palliative medicine and hospice care of veterinary patients seen in the emergent setting.

Dr. Braswell maintains active participation in the community. Historically, her focus has been on providing wellness care for pets of the homeless as well as contributing support of the care of animals in local shelters. She enjoys gardening, performance competition with her canine companion and family. She has two daughters, Kathryn, who has recently graduated and practices in the field of oriental medicine (human), and Veronica, who is completing her second year of veterinary school.

Elizabeth Shull, DVM, DACVIM-Neurology, DACVB


Dr. Elizabeth Shull is Board Certified in Veterinary Neurology (1986) and Behavior (Charter Diplomate 1993). She received her Doctor of Veterinary Medicine
from the University of Tennessee and then completed an internship at Michigan State University. She then followed with a residency in neurology and neurosurgery at the University of Tennessee. 
Dr. Shull was a faculty member at the University of Tennessee, Knoxville for 16 years before starting her private practice in Knoxville in 1999.

Melissa Mays, DVM

Our Veterinarians

Dr. Melissa Mays graduated from the University of West Florida with honors in 2006 with a BA in Exercise Physiology with an emphasis on Pre-Professional Biology. She continued her education at The University of Florida College of Veterinary Medicine where she received her Doctor of Veterinary Medicine in 2009. While at UF CVM she received various awards and scholarships including the Florida Veterinary Medical Association Student Excellence Award and the American Association of Feline Practitioners Award. Dr. Mays then continued to successfully complete a 1-year rotating small animal internship at VCA Aurora and VCA Berwyn Animal Hospitals in Chicago, IL. She recently moved to Chattanooga, TN with her three dogs and enjoys paddle boarding, eating out and the Florida Gators.

Joe Hediger, DVM

Joe Hediger

Dr. Joe Hediger is a proud native of Missouri. He is a true son of the University of Missouri where he received his Doctor of Veterinary Medicine in 2016. Joe completed an externship at RIVER while still in veterinary school, and is thrilled to be back with the team for his internship. Joe has a special interest in emergency and critical care, but is eager to learn from the multiple specialty services available at RIVER. When not treating animals, he can be found either at the crag, the Tennessee River, or any one of the incredible Chattanooga trails. He is an avid rock climber, mountain biker, and competitive water skier. He loves taking his dog Maddie on long hikes and exploring Life with her by his side. When away on adventures, his curious and charismatic cat George guards the house from atop Joe's pillow, thwarting off the ever present threat of spiders and flies. Joe is looking forward to this year and discovering all that Chattanooga has to offer.

Danielle Medoro, DVM

Danielle Medoro

Dr. Danielle Medoro graduated Cum Laude from the College of Veterinary Medicine at Tuskegee University.  Prior to receiving her doctorate degree, Dr. Medoro attended Creighton University where she obtained a Bachelor of Science Degree in Biology. She then continued to pursue her education by attending the University of Georgia where she received a Masters Degree in Animal and Dairy Science. Go Dawgs! 

Dr. Medoro is a native to Colorado Springs and loves everything about the state of Colorado. She enjoys the beauty of the four seasons, the majestic Rocky Mountains, the Denver Broncos, and the various outdoor activities. In her spare time, Dr. Medoro enjoys fishing, football, and spending time with her fiancé, Brad.  Her passions are her two Great Danes, Dolly and Mia; her two cats, Piper and Scarlett; and her two prairie dogs,Alan and Steve. She has a healthy start on her own personal Noah’s arc.

Dr. Medoro enjoys travelling and has participated in many international programs to include a Wildlife immunization clinic in Costa Rica and a spay and neuter clinic in Nicaragua.

However, Dr. Medoro’s most treasured experiences came when she travelled to Thailand for six weeks to work in an elephant sanctuary.  She helped care for over 30 injured elephants and over 400 dogs.  Dr. Medoro’s primary focus is in Emergency Medicine and Critical Care and is very excited for the opportunity to be here at RIVER and experience Chattanooga.

Jessica Allen, DVM

Jessica Allen

Dr. Jessica Allen earned her veterinary degree from Auburn University where she dedicated her free time to coordinating the university's Turtle Rehabilitation Program and serving as a volunteer shift-leader at the Southeastern Raptor Center.  She has a special interest in exotic animals and wildlife and has a pet chinchilla in addition to three dogs.  Dr. Allen is in the final phase of earning the certified aquatic veterinarian recognition from the World Aquatic Veterinary Medical Association.  In her spare time, she enjoys SCUBA diving with her husband and traveling.

Katelyn Thompson, DVM

Katelyn Thompson

Dr. Katelyn Thompson grew up in a tight knit family on the Mississippi Gulf Coast. She is a recent graduate of Mississippi State University's College of Veterinary Medicine and is interested in companion animal medicine, particularly surgery and emergency medicine. She is excited to be in Chattanooga and to be joining the team at RIVER this year. In her spare time, Dr. Thompson likes to go for a run, get crafty, and work in her unruly garden. And of course, life would not be complete without her non-furry fur baby Baldwynn, the Sphinx cat. 

Wayne Zuvers, DVM - Emergency Veterinarian

Dr Zuvers obtained his DVM from Mississippi State in 1999. He began his career in his hometown of Phoenix, Arizona as an emergency veterinarian in 1999. He continued his career in emergency medicine and became the hospital manager for the Blue Pearl Emergency Animal Clinic in Avondale; Arizona. Dr Zuvers made the move to North Georgia in the fall of 2016 when he joined the emergency team at RIVER.

Jessica Rogers, DVM - Emergency Veterinary and Canine Rehabilitation Therapist

Dr. Rogers grew up with a lifelong goal of becoming a veterinarian. She graduated from the University of Tennessee College of Veterinary Medicine in 2015. During school, she developed special passions for physical rehabilitation, oncology, and soft tissue surgery. She has worked at DAC as a vet assistant since 2008 and is honored to still be a part of the team as a veterinarian. As a vet, she enjoys the many opportunities to share God's love for both people and animals. She is certified as a Veterinary Canine Rehabilitation Therapist. In her free time, she loves swimming, hiking, reading, and anything outdoors.