Our caring and compassionate veterinary care team

Meet the Veterinarians and team at Buffalo Mountain Animal Hospital in Dillon, CO. We’re pleased to provide exceptional care for your pets.

Please call us at (970) 513-8400 to speak with one of our staff.

Mark Cowan, D.V.M.


After graduating from Veterinary College at Kansas State University I returned to Colorado to practice at a mixed animal hospital. After deciding to concentrate on small animals I returned to school to pursue a small animal internship. I moved to Summit County in 2000 and opened Buffalo Mountain Animal Hospital in 2004. When I am not working, you can find me enjoying the slopes in the winter and cycling in the summer.

Christine Murphy, D.V.M.


I started working at Buffalo Mountain Animal Hospital in July 2012, but have been working as a veterinarian in Summit County since 1998! I earned my Bachelor of Science at the University of Michigan in Natural Resources/Environmental Science in 1989, and graduated with honors from Michigan State University Veterinary School in 1995 earning my DVM. My husband and I then moved to the Denver area where Dr. Cowan and I first worked together at Broomfield Veterinary Hospital. I moved to Breckenridge in Nov. 1998. Although I completed my education in Michigan, I grew up as a military brat and lived all over the United States. I have always had family ties to Colorado, where my mother was born and raised. Our whole family has a love for the mountains and the outdoors, and you may see me with my husband Peter, two children Mia and Jacob, and two dogs Maple and Finn skiing, biking, backpacking, hiking, or camping. The two cats in the family (Bobbi and Einstein) tend to be couch potatoes and prefer to enjoy the sunshine from the upstairs deck!

Shannon McCollough, D.V.M.


After graduating from Colorado State University Veterinary School in 1990 and completing a 1-year internship at the Sacramento Animal Medical Group in CA, Dr. Shannon McCollough spent the first few years of her career in Denver. She just returned HOME to Colorado after a 28-year absence! She has been a leader in her 30+ years in the veterinary industry. She is a past-president of the Greater St. Louis Veterinary Medical Association (GSLMVA) and has worked on various committees for both the GSLVMA and the Missouri Veterinary Medical Association. Dr. McCollough has been active in Animal Welfare in the last 15 years of her career, including 9 years as a shelter veterinarian and active in various animal welfare organizations in St. Louis. Though she enjoys all aspects of her job as a veterinarian, she is especially interested in internal medicine and dermatology.
Shannon has been married to Mark McCollough since 1989 and they have one child – Luke – born in 2000. The McColloughs currently have 4 pets – 3 dogs and a cat – all named after cars!!!
Shannon and her husband ALSO run a business in South Africa called Global Gift Innovators which creates and sells giftware and provides consulting services to the African adventure travel industry. Shannon’s love of Africa stems from when she was a 17-year-old AFS exchange student to Kenya…If you ever want to go on safari, just ask and Shannon will help you plan a trip-of-a-lifetime!
Shannon has been an active member in political organizations in St. Louis for many years and is now involved with Summit County LAPS. She has also been a committed volunteer in the education sector for 20+ years. She is looking forward to “making a difference” in Summit County!
The McColloughs are avid adventure travelers and have traveled to 53 countries so far and all 7 continents.


Visiting Specialist: Radiologist

Dr. Liz Hoaglund grew up in Indiana and completed her Bachelor's degree in Biology at Purdue University where her love for veterinary medicine was sparked. She graduated from Colorado State University’s College of Veterinary Medicine in 2016 and subsequently went on to Pioneer Equine Hospital in California for a rotating Equine Internship. She then returned to CSU to complete a fellowship with the Equine Field Service prior to beginning her residency in Diagnostic Imaging. Dr. Hoaglund became a Diplomate of the American College of Veterinary Radiology (ACVR) as well as a Diplomate of the ACVR Equine Diagnostic Imaging (EDI) subspecialty in 2021. She enjoys the mixed caseload of specialty/referral and general practice hospitals and is passionate about abdominal ultrasound, musculoskeletal ultrasound and cross sectional imaging, particularly CT. Dr. Hoaglund loves spending her free time enjoying the Colorado outdoors, cooking, traveling, and relaxing with her family, cats and horse.

Vanessa Koehler, D.V.M.

Visiting Doctor

Dr. Koehler is a native of the Chicagoland area, but has lived in 6 states and abroad. After her 1 year experience as a Rotary International Exchange Student in Germany, she was a Division I walk-on student athlete at the University of Miami in Florida, where she earned her BS in Marine Science/Biology. She then worked in chemical oceanography for 2 years, which afforded her some great travel opportunities on research vessels all around the globe (New Zealand, Antarctic Circle, Iceland, Africa, Brazil, and the Caribbean).
Dr. Koehler received her doctorate of veterinary medicine from Ross University in 2007. She completed a rigorous rotating internship Angell Animal Medical Center in Boston, followed by 2 years of postdoctoral surgical training at Animal Hospital Specialty Center in Highlands Ranch and Animal Specialty Group in Los Angeles.
She has published numerous articles in various veterinary journals.
Dr. Koehler enjoys all aspects of veterinary medicine and its constant challenges. Most of all, she enjoys getting to know her clients and patients.
Dr. Koehler has been practicing medicine in Summit County since 2011. When not working, you can often find her enjoying Colorado’s outdoor playground or traveling. She has traveled as far as Fez, Morocco and South Africa for volunteer efforts as well.

Jacob Ammon

Veterinary Assistant

Jacob has resided in Breckenridge his entire life. He started working here full time as an assistant after graduating from Summit High in Spring 2021. He shares his love for animals with his mom, Dr. Murphy! In addition to working, Jacob has been earning credits from the local CMC in Breckenridge and plans to transfer to a 4 year university.

Suzanne Flachier

Certified Veterinary Technician

I grew up in South West Michigan and moved to Colorado about 12 years ago to attend Veterinary Technician School. After graduating in December 2011, I moved to Summit County. My four-legged family consist of a dog named Rodent, a cat named Percy, and 2 horses. In my spare time you can find me throwing a frisbee/ball for my dog, hiking, photography, horseback riding, and lake kayaking, My goals this summer are to climb my first 14er and learn to fly fish!

Adam Awadallah

Veterinary Assistant

I am new to Colorado and recently moved to Summit County in Fall 2021. I have previous veterinary experience in ER and Cardiology and I’m excited to be working in my first general practice. I have a background in wildlife rehabilitation and I worked with wild birds and sea lions in California. In my free time I enjoy hiking, snowboarding, art and music. Unfortunately, I don’t have any pets but I would love to someday own a Siamese cat or a couple huskies. Maybe all three if everyone gets along with each other!

Kaitlin Norman

Veterinary Assistant

Kaitlin was born and raised in Bristol, Tennessee . She has lived in Leadville, Colorado for close to 2 years now and loves being able to call Colorado home. Kaitlin graduated from East Tennessee State University with a bachelor’s degree in Human Services and Psychology in 2018. Although she originally planned to work with humans, she decided she liked furry friends instead. Kaitlin works as a veterinary technician here and really enjoys all of the animals she gets to interact with. She has two crazy Australian Shepherds named Finn and Nipsey that she loves more than anyone. In her spare time, she loves to snowboard, hike, walk her dogs, and drink coffee.

Sydney Simpson

Veterinary Assistant

Sydney has been working in the veterinary field since she was 16, and graduated with a Biology degree from Colorado State University in 2020. She spent 3 years working in the critical care unit at CSU’s Veterinary Teaching Hospital, where she still works part time doing emergency medicine and clinical research. Sydney is an author on 3 peer reviewed studies related to veterinary medicine. In her free time, Sydney enjoys snowboarding, hiking with her 2 dogs (Rosie the yorkie and River the border collie), and weight lifting. Sydney also has a hedgehog named Fish who is a fan favorite here at Buffalo Mountain.

Melissa May

Veterinary Assistant

Melissa is originally from Rockford, IL. She moved to Colorado about 8 months ago. She has a bachelors degree in Animal Ecology and Wildlife Care from Iowa State University. She has worked as a veterinary technician on and off over the years. She took a break for a while and worked at a big cat rescue doing animal care and then spent 5 years teaching environmental education and recreation while also training and caring for raptors and reptiles. She has a passion for all creatures big and small. She currently has her own wonderful animal family that consists of a dog, 2 cats, and a beautiful boa constrictor.

Heather Collins

Veterinary Assistant

Heather was raised on a ranch North of Silverthorne, and has worked with all sorts of animals including horses, cattle, chickens, etc. At Buffalo Mountain Animal Hospital she currently works as a veterinary assistant. She is cold laser certified and is currently taking ACT courses. She hopes to own a ranch with all kinds of animals, and possibly start studying Equine Vet Care. Heather's hobbies include playing the ukulele and art. She tries to get out for camping, fishing/ice fishing, and traveling to new parts around the area as much as she can. She has fallen in love with working with animals and is very happy to a part of the Buffalo Mountain Animal Hospital family!

Emily Jacobs


Emily grew up North of Silverthorne part of the time and in Denver the rest. She has lived in the Pacific Northwest, Fort Collins, Indian Hills, and Spain, but is tickled to be in the Blue River Valley again. She has a BA from DU and a certificate in Animal-Assisted Therapies, Activities and Interventions from DU’s Graduate School of Social Work. She recently completed an Equine Science degree at CSU and on top of working at Buffalo Mountain Animal Hospital she also owns a horse training company. Her first small animal work was at the Humane Society of the South Platte Valley. She takes every opportunity she can to walk her dogs, Tuvia and Dally Girl, and she also spends as much time as she can camping, snowboarding, and reading. She can be found at the front desk at Buffalo Mountain and she is honored to work for such caring and compassionate vets!

Abby Shotts

Veterinary Assistant

Abby is originally from Bucks County, PA. She graduated high school in 2009 and went to Boston University and received a BA in Biology. She spent the next 3 years working for the MSPCA Adoption Center in Boston where she discovered she has a passion for behavior modification and low stress handling. Abby moved to Summit County in July of 2017 to be closer to friends and enjoy life in the mountains. Her hobbies include hiking, skiing, reading and spending time with her rabbit, Pippi and dog Layla.

Ben Laidlaw

Veterinary Assistant

Hiya, I’m Ben, a rising senior at Colorado College majoring in Molecular Biology on the Pre-Vet track. I’m originally from England, but moved around growing up.. so I unfortunately lost the accent. I’m on the swim team at CC, and love spending time with animals.

Killy McKernan


Killy was born in Hoodriver Oregon and grew up in Summit County. She currently lives outside of Silverthorne on Green Mountain Reservoir. She has been involved in working with animals her whole life, and had a 3 year long internship at Summit County Animal Shelter in Frisco. Her passion for helping animals has been there since she was a little girl, even then hoping one day to work with any and all animals. Killy’s hobbies include building Long boards in her shop, skiing, music, and traveling with her dog Harley and family dog Jack.

Heather McAlexander - Tomchuck

Certified Veterinary Technician

I obtained my BS at Appalachian State University, then decided to pursue my veterinary technician degree at Bel Rea Institute of Animal Technology in Denver, Co. After finishing veterinary technician school in 2001, I completed internships at both Alameda East Veterinary Hospital and Littleton Large Animal Clinic. I love veterinary medicine, but have a special affinity for surgery. I like to spend my free time outdoors with my husband Chris, our two boys, Wes and Sam and our two dogs, Lucy and Larry.

Emily Hirshman

Veterinary Assistant

Emily is a rising senior at Carleton College, where she majors in psychology and minors in neuroscience and Spanish. She has always had a passion for working with animals, and plans to apply to veterinary school after she graduates from undergrad. Emily spent last summer interning in a veterinary clinic, and while at school she walks professors’ dogs and works in a cognitive research lab taking care of cotton-top tamarin monkeys. In her free time, Emily enjoys hiking, biking,doing puzzles, and spending time with her rescue dog Juno.