Our Team
Dr. Ariel Fagen, DVM, DACVB
Board-Certified Veterinary Behaviorist
Medical Director
Dr. Fagen graduated from Tufts University Cummings School of Veterinary Medicine in 2013.  She went on to complete an intensive one-year rotating small animal internship at Wheat Ridge Animal Hospital.  In 2017, she completed a 3-year residency in the American College of Veterinary Behavior at Behavior Vets of Colorado and Florida Veterinary Behavior Service.  In 2018, Dr. Fagen became a Diplomate of the American College of Veterinary Behavior, the highest level of veterinary behavior specialty degree possible.  This degree makes her one of 86 of the most highly trained veterinary behavior specialists on the continent and one of two veterinary behaviorists in the state of Colorado.  
Outside of the office, Dr. Fagen has lectured in the US and internationally.  She has conducted research studies in shelters, hospitals and wildlife breeding centers and has published in the Journal of Applied Animal Welfare Science, AAHA Trends Magazine and NAVC Clinician’s Brief.  Dr. Fagen was awarded the American Veterinary Society of Animal Behavior Student Excellence in Applied Animal Behavior Research Award and the Tufts University Cummings School of Veterinary Medicine Best Field Research Award for her work training elephants to participate in their own medical care in Sauhara, Nepal.  She currently serves on the Fear Free Advisory Board. 


A Colorado gal to the core, Dr. Fagen plays in the mountains hiking, camping and downhill and cross-country skiing.  She loves to travel with her adventuresome husband, giggle with her young son and share meals with friends. The four-legged love of her life, Libby, was with her through her veterinary education and taught her a great deal about living with and loving a dog with aggression problems. 

Dr. Stacey Jones, DVM
Veterinarian - Practice Limited to Behavior
Fear Free Certified

Dr. Stacey Jones graduated from Colorado State University’s College of Veterinary Medicine in 2003.  After graduation, she completed a one year internship in Emergency Medicine and Critical Care at New England Animal Medical Center in Massachusetts. Returning to her native state of Colorado, Dr. Jones cultivated a special interest in Greyhound medicine, anesthesia, behavior and pain management.  She is proud to have participated in collaborative research into a life threatening elevation of blood potassium (hyperkalemia) that occurs in Greyhounds under anesthesia.


During her 16 years as a small animal veterinarian, Dr. Jones cultivated a practice focused on decreasing fear, listening to patient body language and including families in veterinary visits.  In this way, she could increase access to detailed care for all patients, especially those historically demonstrating anxiety or reacting aggressively.  Providing for medical needs through this behavioral lens led Dr. Jones on a journey to further understand and treat problem behaviors that were causing frustration and suffering for patients and their people, in and out of the hospital.  Dr. Jones furthered her education in the field of behavior and veterinary psychiatry through mentorship with field experts, attendance at the national Clinical Animal Behavior Conferences, and coursework on learning theory and applied behavior analysis, including Dr. Susan Friedman's course, Living and Learning with Animals.  Before coming to The Veterinary Behavior Center, Dr. Jones treated behavior cases within the scope of her general practice for 7 years.  She is currently a Fear Free certified professional and serves on the executive board of the American Veterinary Society of Animal Behavior as a member-at-large.  

Dr. Jones, her husband, and their two children, share a home with numerous dogs, horses, chickens, and aquatic creatures.  

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Dr. Asher Feldman, DVM
Veterinarian, Pursuing a Residency in Veterinary Behavior
Fear Free Certified Elite

Dr. Asher Feldman graduated from Tufts University Cummings School of Veterinary Medicine in 2021.   It was in veterinary school that Dr. Feldman discovered his passion for veterinary behavior, taking every opportunity he could to spend time with the behavior department there.  After graduation, he completed an intensive one-year rotating small animal internship at Friendship Hospital for Animals in Washington, DC. 


Through veterinary school and his internship, Dr. Feldman built on prior experience training horses and dogs to develop and refine a passion for veterinary behavior.  He loves research and is currently involved in multiple studies, including one on the behavioral effects of progressive vs. sudden blindness in dogs.  He has pursued additional education outside of his veterinary degree and internship in behavior including the completion of a Human-Animal Bond certification. 


In his spare time, Dr. Feldman enjoys sewing, board games, and science fiction. He shares his home with his partner and a perfect labrador mix named Padfoot, who has guided him through helping a dog with behavior problems adapt and flourish.

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Bridgette Chesne
Relationships and Programs Manager
Fear Free Certified

Bridgette joined The Veterinary Behavior Center in 2022 after a long and loved career at the Humane Society of Boulder Valley. For more than 25 years, Bridgette’s leadership at HSBV included the positions of Director of Animal Behavior and Sheltering, Community Resource Manager, and Volunteer Manager. Bridgette enjoys developing programs that advance a learner’s capacity to objectively assess animal behavior with a goal of low-stress handling and opportunities to reinforce desired outcomes. A self-proclaimed junkie for scientific literature, Bridgette enjoys her role of lifelong learner and hopes to engage others along the way. Curating and maintaining healthy relationships between pets and people are the cornerstones of Bridgette’s commitment to animal welfare. She joins The Veterinary Behavior Center with her Fear Free ™ certification and plans to achieve her Karen Pryor Certified Training Partner credentials this year. Bridgette and her husband, Greig, own the Barking Dog Café in Lyons, Colorado, and love spending time in the outdoors with their son, Landin, a University of Colorado Boulder graduate. Bridgette shares her home with two dogs, the most magnificent cat, and three box turtles.

Danielle Winkelman, KPA-CTP, ACDBC
Learning & Development Team Lead
Fear Free Certified
Karen Pryor Academy Certified Training Partner
Associate Certified Dog Behavior Consultant

After serving in the military as an Army medic, Danielle Winkelman graduated with a Bachelor of Science in Biology from the University of North Carolina.  Her career with animals began in shelters and sanctuaries, including Asheville Humane Society, where she was a veterinary assistant. Reluctant to give up rescue work, when Danielle accepted a position in an animal hospital, she started a nonprofit dog rescue. This is where she gained an appreciation for working with behavior issues and helping shelter pets become family members. Now with over a decade of experience in veterinary medicine, she continues to volunteer with a variety of species, from pigs to parrots. 


Danielle racks up a list of top level certifications in the dog training and veterinary handling world.  She is a Karen Pryor Academy Certified Training Partner, one of the most well-respected dog training certifications in the country.  She has also earned her credentials as an Associate Certified Dog Behavior Consultant, a certification process that assesses both science-based understanding of how pets learn as well as appropriate application of this knowledge.  She is a Fear Free™ Certified Professional which means she has additional training making the veterinary experience low stress and is a Puppy Start Right Certified Instructor, ready to help puppies get set up for a lifetime of good manners and success in our human world.  Danielle is a graduate of “Resolving Fear Issues in Horses” through the International Association of Animal Behavior Consultants, has worked with the Allegiance Rescue and currently volunteers with the Great Escape Mustang Sanctuary.  She seeks out every opportunity for continuing education on the science of animal behavior and learning and has attended multiple conferences including the International Association of Animal Behavior Consultants conference, Clicker Expo, Advanced TAGteach workshop, Living and Learning with Animals Professional Course run by the renowned Susan Friedman, PhD, and the Art and Science of Animal Training Conference, and more.


She shares her home with her boyfriend, two huskies, a mustang, poultry, alpacas, and a mixed-breed pup who gives her plenty of opportunities to practice behavior treatments. She enjoys exploring the outdoors and can also be found practicing martial arts.

Mariah Dingus, CBCC-KA
Learning and Development Lead
Certified Behavior Consultant Canine

Mariah began accumulating professional experience with animals at a young age as a volunteer keeper aid at the Houston and Cheyenne Mountain Zoos throughout high school and college.  In these positions, she taught animals from rhinos to grizzly bears to participate in cooperative vet care and learned a great deal about enrichment and the humane care of captive wildlife.  During her internship at the Penn Vet Working Dog Center in Philadelphia, she learned to apply her knowledge of training and cooperative care to dogs training for careers in search-and-rescue, law enforcement, and ovarian cancer detection. 


It wasn’t until her externship with veterinary behaviorist Dr. Lore Haug that Mariah discovered her true passion for a slightly different side of dog training: behavior modification.  In this position, Mariah assisted in addressing behavior cases from generalized anxiety to various types of aggression, honing her skills in identifying behavior problems and how to solve them benevolently and from the source, in the best interest of both dog and owner.


After graduating from Colorado College in 2019, Mariah took up a position at Canis Major Dog Training as a trainer.  There, in addition to teaching classes and training board-and-train dogs, Mariah worked one-on-one with clients whose dogs were struggling with behavioral issues from resource guarding to stranger danger.  In 2021, Mariah passed her CBCC-KA exam, a rigorous exam verifying her knowledge-base and certifying her as a top-level dog trainer and behavior consultant, equipped to handle serious behavioral challenges.  Mariah’s favorite part of the job was being there to support her clients throughout their behavior plans and building a relationship of trust and open dialogue along the way.


Mariah shares her home with a perfect mutt named Peanut who literally wandered into her life. Peanut has given a hands-on opportunity to learn the ins and outs of separation anxiety and helps Mariah empathize with every client who owns a squirrel-obsessed dog.  

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Oak Thorsen, CVT
Veterinary Behavior Nurse
Karen Pryor Academy Certified Training Partner
Fear Free Certified
Certified Veterinary Technician

Oak has had a passion for animals from a very young age. They grew up with working sled dogs, horses, and a variety of pet dogs and cats. In 2016 they graduated from Carroll College with a Bachelor’s degree in Anthrozoology, study of the human animal bond. During their time in school, they volunteered at a wild-life rehabilitation center and assisted a local trainer in puppy classes.


Oak went on to earn an Associates degree in Veterinary Technology from Colorado Mountain College. During that time they grew passionate about low stress handling of animals during veterinary visits and empathy for the humans caring for those pets. This led them towards veterinary behavior as an intersection of the human-animal bond and veterinary medicine.  They currently are enrolled in the Karen PRyor Academy Certified Training Partner course.


Oak lives with a standard poodle named Mabel, a mutt named Wynonna, and a Japanese bobtail cat named Dipper. Oak enjoys hiking with their dogs, teaching their dogs silly tricks, and drawing in their down time.

Sarah Swing, KPA-CTP
Behavior Therapy Technician
Karen Pryor Academy Certified Training Partner
Fear Free Certified

Sarah’s passion for animals and their welfare led to a variety of animal care opportunities, including working or volunteering for a safari park, zoo, dog daycare, and animal rescue. Upon adopting her dog Zuri, she became interested in training and behavior as she navigated Zuri’s dog reactivity and body handling sensitivities.

Working as a behavior technician under veterinary behaviorist Dr. E’Lise Christensen provided Sarah with valuable insight and experience helping clients whose pets exhibited challenging behaviors. From there, she worked hands-on with a variety of dogs and cats at the Humane Society of Boulder Valley as an adoption specialist, counseling clients as they chose the right pet for their family.

These opportunities solidified Sarah’s commitment to animal welfare through supporting their behavior needs, and sparked a new passion for assisting pet guardians during pet behavior treatment. Sarah is a Fear Free Certified professional, Certified Training Partner through the Karen Pryor Academy and pursues additional education and certification through classes and webinars. She shares her home with her husband, dog, and three rats.

Sarah Hahnenberg
Operations Manager (and Master of Getting Stuff Done)
Low Stress Handling Silver Level Certified
Fear Free Certified

Sarah graduated from Colorado State University with a Bachelor’s of Science in Biology in 2008, is a certified EMT-B, IV, and is in the final stages of obtaining her Medical Laboratory Technology Degree. With 12 years of experience as a veterinary technician, Sarah is certified in Low Stress Handling and Fear Free medicine and loves to help furry friends have a positive experience with their veterinary care. She is passionate about helping pets and their guardians navigate their way through both their medical and emotional needs.  


Sarah's role supports the overall daily functioning of TVBC.  She assists with designing, managing and overseeing the operations systems that enable the business to function. Her wide range of skills helps keep the business on track, from operational organization to diagnostic management, as well as supporting the employees and their various roles on the TVBC team.


In her spare time, Sarah is an avid stand-up paddle boarder -- you can find her out on a lake almost every weekend (weather allowing). She also loves to hang out with her two border collies, Kash and Kaiya, and enjoys adventuring with her husband and her beautiful daughter.

Lola Wallen
Client Experience Rockstar
(any pronouns)

Lola, a native of upstate New York, moved to Colorado in the summer of 2020 after living in Charleston for 3 years. Although they graduated with a bachelor's degree in Music, Lola has been working with animals for over a decade, providing services as an in-home pet sitter working as an office administrator for animal daycare, boarding, and training facilities.


Lola is passionate about helping others -- animals and humans alike -- and is eager to explore how their skills and interests can contribute to the welfare of pets and their people. They share their life and home with their dog, Poppy.