Meet our amazing veterinarians!
Dr. Marshall Kohr
Hospital Director / Veterinarian / Partner
During high school, Dr. Kohr worked on a farm and developed a strong admiration for the individuals he worked with. He went in search of a profession that allowed him to work outdoors and contribute to the livestock industry—a career in veterinary medicine was the perfect answer!
Marshall grew up in Millersville, Pennsylvania, in agriculturally-based Amish Country. In 1985, he started veterinary school at Colorado State University, graduating along with his classmate and future business partner Dr. Darren Lynde in 1989. While Dr. Lynde returned to his hometown of Gillette, Dr. Kohr practiced in a livestock clinic in Bridgeport, Nebraska. Two years later, he reconnected with Dr. Lynde and moved to Gillette, where the pair started their own practice in the spring of 1991.
Professionally, Dr. Kohr is interested in the diagnosis and treatment of equine lameness. He also enjoys the challenge of equine reproduction. He is proud of all the different perspectives, skills, and personalities the staff of the Animal Medical Center bring and is always excited to come work with such a great group of people.
Marshall is married to his wonderful wife, Lynn, who Dr. Kohr says is one of the best horsemen in the Rocky Mountain region. He also has three children, two in High School and one in Junior High. He loves watching his wife and kids compete in barrel racing, and attending his kids’ hockey, basketball, and other sporting events.
Dr. Kohr serves in the Wyoming Army National Guard as a Colonel!
Dr. Nate Zieman
Veterinarian / After Hours On-Call Veterinarian
Dr. Zieman graduated from Iowa State University in 2000 with his DVM. He purchased a clinic in New Rockford, North Dakota, in 2001, and purchased an additional clinic in Devils Lake in 2002. He sold the practices in 2010 and 2012 and came to work as the after-hours on-call Veterinarian at the Animal Medical Center.
Nate grew up in Sheyenne, North Dakota, where he enjoyed playing sports and participating in rodeos. Before moving to this area, he worked in a mobile bovine clinic for two years.
At home, Dr. Zieman lives with his wife Tracy, their 7-year-old Koy, 4-year-old Tyler, and 3-year-old twins, Trey and Kynlee. When time allows between work and family, he enjoys team roping and hunting.
Dr. Brad Powell
Associate Veterinarian
For as long as he can remember, Dr. Powell wanted to be a part of the agricultural industry. He realized that veterinary medicine was a great way to combine his professional interests with his love of animals!
Brad grew up in Texas and attended Abilene Christian University to obtain his Bachelor’s degree in Animal Science. He went to Texas A&M’s College of Veterinary Medicine for his veterinary degree, and worked at a practice in Abilene for two years after graduation. In the fall of 1999, he joined the team at the Animal Medical Center as an Associate Veterinarian.
Dr. Powell enjoys the challenge of jumping from one species to another as a mixed-animal practitioner. He’s especially passionate about equine lameness and equine dentistry cases.
Brad has been married to his wife Melissa for 26 years. Together, they have three children: Kolten, who graduated from the University of Wyoming and serves along with his wife Katie, as a campus minister at the University, Brenna, a student at the University of Wyoming, and Mason, a high school student who enjoys playing hockey and baseball.
Dr. Powell’s interests outside of veterinary medicine include fly fishing, hunting, reading great books, coaching youth sports, and learning about history. Brad considers himself a life-long student and learner.
Dr. Darren Lynde
Veterinarian / Senior Partner
Before deciding to become a veterinarian, Dr. Lynde had a few professions in mind: working with people, working in the medicine field, or caring for animals. He then realized that being a veterinarian combined all three!
Dr. Diane Ernst
Associate Veterinarian (part time)
Having grown up in Gillette, Dr. Ernst decided in the sixth grade that she wanted to be a veterinarian. She never grew out of it, and now serves as an Associate Veterinarian at the Animal Medical Center!
Diane attended veterinary school at Washington State University. After practicing in Glasgow, Montana, she joined the Peace Corps for three years. After that, she practiced in Belt, Montana before returning to her hometown of Gillette. She joined the team here at the Animal Medical Center in September of 1996.
As a vet, Dr. Ernst loves working with kittens and puppies and helping to make their first visits not so scary. She also enjoys offering training and care tips to owners to ward off potential behavior problems.
In her free time, Diane enjoys reading, riding horses, singing in the community choir, and helping out on her friend’s ranch. She also has two dogs of her own, both adopted from the local shelter, Border Collies: Jess, a ball fanatic, was adopted from a local shelter, and Dodge, who is gradually coming out of his shell. Her 16-year-old kitty, Boots, does what he wants when he wants!
Dr. Erin Innes
Associate Veterinarian
Dr. Innes started her veterinary career in high school when she worked as a technician at an equine-exclusive hospital. The veterinarian there told her that he never hesitated to get up and go to work in the mornings because he loved what he did. Erin wanted that as well, and was inspired to become a veterinarian herself! Born in East Texas, Dr. Innes attended Texas Christian University in Fort Worth for her undergraduate degree, then went to Texas A&M for veterinary school. In 2011, she moved to the Gillette area and joined the Animal Medical Center team shortly afterward. Erin lives with her husband, Kyle, and their beagle, Toby, who enjoys chasing rabbits. They also have four Arabian horses, Ogee, TJ, Laurie, and Oran. When time allows, Erin enjoys endurance racing with her horses, traveling, snow and water skiing, and spending time with family and friends
Dr. Rachel Young
Associate Veterinarian (Small & Large Animals)
Growing up on a hog farm in Ohio, Dr. Young has always been around animals. Since she was a young girl, her mind was made up to become a veterinarian. She never wanted to do anything else, and her hard work and dedication paid off—now she’s an Associate Veterinarian at the Animal Medical Center.
Rachel spent four summers working at a guest ranch in the Big Horn Mountains outside of Buffalo, Wyoming. She absolutely loved the area, and started to look for a veterinary clinic nearby. In July of 2013, she started at the Animal Medical Center. She especially loves meeting people and their pets, and is constantly rewarded when she hears back from clients that their sick pet is doing well again.
Outside of work, Dr. Young enjoys horseback riding and hiking in the mountains, which she often does with her horse, Rusty. She also loves photography and scrapbooking, and likes to read and write when the weather isn’t agreeable.
Dr. Susan Lucas
Associate Veterinarian
Susan was born and raised in North Dakota, where she spent summers at her grandparents’ farm. The closest veterinarian was over 50 miles away, so they frequently had to treat their animals themselves. Helping out with the animals inspired Susan to become a veterinarian herself when she got older!
After two years of pre-veterinary medicine studies at North Dakota State University in Fargo, Dr. Lucas was accepted into veterinary school at Kansas State University. After practicing in North Dakota at a small animal practice, Dr. Lucas realized she missed the mountains and working in mixed-animal practice, so she came to Gillette in 1992.
At home, Susan has several pets of her own: three Sussex spaniels, a Scottish Fold cat, and a desert lynx cat. She’s been training and competing in obedience with her dogs for many years now. Dr. Lucas also enjoys hiking in the mountains with her dogs and has even been on several overseas trips for long-distance hiking.
Dr. Jen Hefftner
Associate Veterinarian
Both Dr. Jen Hefftner’s father and mother have had long careers in the human healthcare world, so she has harbored a passion for medicine and science ever since she was a young girl. She’s also adored animals for as long as she can remember. Why not couple her love for the earth’s creatures and her fascination with science, Dr. Hefftner mused, by working in the field of veterinary medicine? She hasn’t looked back since!
Dr. Hefftner grew up in Albuquerque, New Mexico, where she started her animal-care journey by working as a Veterinary Assistant at the age of 15. She then attended Colorado State University to earn both her Bachelor’s degree in animal science and her Doctoral degree from the school’s College of Veterinary Medicine, finding time between her studies to help raise puppies for the Guide Dogs for the Blind program.
Dr. Hefftner joined the Animal Medical Center of Wyoming team in June of 2016, and couldn’t be happier to practice high-quality veterinary medicine in a warm, welcoming family atmosphere. Medically, her favorite parts of her job are internal medicine cases and critical care work; she never tires of the fast-paced problem solving needed to arrive at a solution. Most of all, though, Dr. Hefftner enjoys getting to know the pet owners of the area on a daily basis.
Away from the office, Dr. Hefftner enjoys hiking and fishing in the great outdoors and is currently learning to snowmobile. She’s also an avid dancer, and even taught tap dance during veterinary school. Dr. Hefftner and her husband, who owns and operates a welding and excavating company, share their lives with several pets: Maple, an energetic bloodhound puppy who is constantly getting into trouble; two rescued cats named Shakespeare and Cinder who rule the house; and four playful goats who go by Kya, Ruby, Soda, and Mari.
Dr. Kalisch
Veterinarian
Bio coming soon.