Martin G. Crabo, DVM
Equine Sports Medicine

General Equine Practice

Dr. Crabo joined Chaparral Veterinary Medical Center in 1991. He graduated from the University of Minnesota, College of Veterinary Medicine in 1990 and subsequently completed an internship in Large Animal Medicine & Surgery at Washington State University. Dr. Crabo is married to Barbara, an Eventing Trainer having completed the prestigious Rolex Kentucky CCI****. Together they have a daughter named Jordan (also an avid Eventer), 14 horses, 3 dogs, 3 cats, and a Cockatoo on their "ranch," Four Peaks Farm. When the family gets a rare chance to get away, the Crabos enjoy horse shows, show skiing, and the ocean together. Professionally, Dr. Crabo's interests include equine sports medicine, lameness and imaging as well as general equine practice. He strives for an in-depth knowledge of equine ultrasound and anatomy through his mentorship in ISELP, the International Society of Equine Locomotor Pathology.


C. Renee Andrea, DVM, Dipl ACVS 
Equine Veterinarian Surgeon

Dr. Andrea joined Chaparral in December 2001, as our first board certified surgeon. She is a 1994 graduate of Washington State University's College of Veterinary Medicine, after which she completed an internship here in Arizona. She then spent three years at the University of California at Davis as a resident in equine surgery, where her area of research was in equine orthopedics. Dr. Andrea became a diplomate of the American College of Veterinary Surgeons in 1999. Although she specializes in all area of equine surgery and lameness, Dr. Andrea's major interests are in equine orthopedics, reconsructive surgery, and horses with acute abdominal disease. Dr. Andrea and her husband Mike Freeland reside in Desert Hills, Arizona. They have two sons, Canon and Shea. Together they enjoy a lot of outdoor activities, but most of their time is spent with the family's rope and barrel horses

Alison Ariano, DVM

Small Animal Veterinarian

We are very excited to welcome Dr. Ariano to our team as of May 2014.  Dr. Ariano is joining our Small Animal department as we expand to a two doctor practice.  Dr. Ariano has nearly seventeen years of experience in Small Animal Medicine.  Dr. Ariano's special areas of interest include Internal Medicine and Canine and Feline Dentistry.  Dr. Ariano is originally from Chicago, Illinois, but has lived in Arizona for fifteen years now.  In her free time she enjoys spending time with her husband and two young boys and her rescue dogs, Campari (a Red Heeler mix) and Marty (a Rat Terrier mix).  She also enjoys running full and half marathons. 

Rachel Liepman, DVM, Dipl. ACVIM

Equine Board Certified Internal Medicine Specialist

Dr. Liepman joins Chaparral from the Midwest, hailing from Michigan.  A wolverine at heart (her alma mater), Dr. Liepman graduated in 2011 from Michigan State University, College of Veterinary Medicine with a Doctorate of Veterinary Medicine and went on to complete an internship in equine sports medicine, surgery and internal medicine at BW Furlong and Associates in New Jersey. Thereafter, she pursued further training as an internal medicine specialist at The Ohio State University.  During her residency, Dr. Liepman was involved in several different areas of research in equine medicine including topics in neonatology and gastrointestinal health.  Board certified in Equine Internal Medicine, Dr. Liepman especially enjoys the challenge of a difficult case and working up critical emergencies.  Dr. Liepman spends her free time exploring the outdoors with her husband, toddler, and their dog, Penelope (blue heeler). 

Wade T. Walker, DVM, Dipl ACVS

Equine Board Certified Surgeon

Equine Sports Medicine 

Dr. Walker is a southern California native and comes from a long lineage of veterinarians. He attended Colorado State University for both his undergraduate and veterinary degrees, where he graduated with honors. During this time Dr. Walker was on staff at the Equine Orthopaedic Research Center and was involved in numerous studies investigating the progression and prevention of equine osteoarthritis using different medical therapeutics and surgical interventions. Following completion of veterinary school, he completed an internship at Arizona Equine Medical and Surgical Centre in Gilbert, Arizona. He accepted a position at Cornell University for a three year Large Animal Surgical Residency. Dr. Walker worked as an Associate Surgeon at San Luis Rey Equine Hospital prior to joining the team at Chaparral Veterinary Medical Center. Currently, Dr. Walker is a board certified equine surgeon and a Diplomate in the American College of Veterinary Surgeons.  

Dr. Walker has published several scientific manuscripts in veterinary orthopedics, upper respiratory surgery, traumatology, and colic and presented his research nationally at several conferences. A list of selected publications can be accessed at the following link (https://www.researchgate.net/profile/Wade_Walker/contributions). His clinical interests include orthopedic, upper respiratory, and oncologic surgery, as well as regenerative medicine and lameness. Dr. Walker is also available for consultation on ruminant orthopedic surgery.        

Karin Thomasson, DVM

Equine Veterinarian
Dr. Karin Thomasson was raised on a farm in the great state of Minnesota, where her love for horses and the outdoors began.  She waited seven long years to get her first horse and then spent much of her time growing up horseback—training, trail riding, showing, and roping.  She realized her passion for veterinary medicine while being able to help their veterinarians deliver calves, perform surgeries, and treat her horses on the family farm.   Dr. Thomasson attended North Dakota State University as an undergraduate, majoring in Animal & Range Science and Equine Studies.  During her time as an undergraduate, she worked as an intern at Peterson & Smith’s Equine Reproduction Center in Ocala, Florida, which clinched her desire to pursue equine veterinary medicine.  Dr. Thomasson spent four years in Manhattan, KS at Kansas State University for veterinary school.   Upon graduation she moved to Glenwood Springs, Colorado completing an equine veterinary internship at Glenwood Veterinary Clinic.  She enjoys all aspects of equine medicine, especially, dentistry and sports medicine.  In her free time, Dr. Thomasson enjoys horseback riding, training, and roping with her husband, Johann, traveling, and anything outdoors.

Anastasia Keyser, DVM

Equine Veterinarian

Dr. Anastasia Keyser joins Chaparral from Texas.  Although she did not get the opportunity to grow up on a ranch, her family always had horses.  She was riding before she could walk and continues to maintain that passion for horses.  Dr. Keyser initially received a BA in business administration majoring in business management.  Her decision to pursue veterinary medicine followed a few years later after realizing that she wanted to do even more to help horses besides training them and running a 501(c)3 horse rescue. She attended Texas A&M University’s College of Veterinary Medicine and Biomedical Sciences.  During her time in College Station, she was employed in the large animal ICU at Texas A&M Veterinary Medical Teaching Hospital.  After veterinary school, she completed an internship at Reata Equine Hospital in Weatherford, TX.  She currently owns 5 horses and 3 dogs.  Dr. Keyser enjoys all aspects of equine medicine especially dentistry, reproduction, and sports medicine/podiatry.  Dr. Keyser enjoys spending her free time outdoors through trail riding, horse shows, hiking, camping, scuba diving, skiing, and traveling.  


J Brent Rollins, DVM Emeritus
Equine Veterinarian
Dr. Rollins originally founded Chaparral in 1971 and retired at the end of 2012 after 45 years as an active practicing veterinarian. He is a 1967 graduate of Colorado State University where he received his DVM. He grew up in Phoenix, attending Osborn grade school, Washington High School and Arizona State University. His interest in horses came from his dad's Thoroughbred Racing Business (started on the end of a pitchfork and ended up with a trainer's license before Vet School).

After receiving his DVM, he served for three years as a captain in the US Army in Fort Detrick, MD. After the service, Dr. Rollins completed an Equine Internship at the University of California, Davis, Veterinary Teaching Hospital. In July 1971, he entered private equine practice in North Phoenix.

 Dr. Rollins feels his greatest accomplishment is his family. Brent and Francie have been married since June 1st, 1963. They have five children and 25 grandchildren (at last count) and these days of retirement are spent keeping up with all their activities.

Gemma Cock, BVetMed, MRCVS


Gemma was born and raised in England, UK. Prior to vet school she lived in California where an undergraduate degree in Biology was completed. Gemma returned to the UK for vet school and graduated from the Royal Veterinary College in July 2016. After graduation, she moved to Arizona to begin an internship at Chaparral. Gemma has always had a passion for horses and enjoys spending time with her Connemara mare, Lily, who she bred, raised and competed in 3-day eventing. She also enjoys spending time with her cat, Harry, whenever she can. 

Brandt Cassel

Practice Administrator

Brandt is originally from Southern California and has spent many years in healthcare management and operations positions. He has a BS in Organizational Management from the University of La Verne, and a MBA in Healthcare Administration from the University of Saint Mary. Brandt enjoys spending time with his dogs Loki and Elvira, and Lemmy the Cockatiel. He and his beautiful wife, Heather, enjoy beach camping and spending time with their two lovely granddaughters.

                                                                    Susan Dixon


      Suzan Rockvam

       Administrative Assistant

Originally from central California, but lived in the Scottsdale area for decades.  I've ALWAYS loved animals with a passion.  I've raised poodles and Lhasa Apsos in the past, and now am the proud owner of 2 rescue dogs: Sally (a jet-black corgi mix,) & Sunny (a buff cockapoo mix.)  Satisfied my equine passion by completing the Equine Science program at SCC resulting in an A.A.S. In Equine Science.  Spent many years as Office Manager at Southwest Equine Hospital in Scottsdale, also employed in Administrative positions in Retail, Real Estate, Health Care and now back to Veterinary.  I am enjoying working in this wonderful practice!  My many hobbies include fitness, music and travel, but spend most of my time enjoying my home and teenage son, Robert.


Heather Bermijo

Pharmacy Technician, CVT

Heather was born and raised right here in Phoenix, Arizona. She has a son and daughter, two dogs, two birds, and a number of salt and freshwater fish. As long as Heather can remember she has had a deep love for animals, and as she has grown older she has gained a deep respect for them as well. This is why Heather decided to enroll in the Long Technical College's Veterinary Technician Program. Upon her graduation, Heather began her career in an alternative medicine veterinary office. Now she is continuing her ongoing education here at Chaparral Veterinary Medical Center.


Jamie Pfeiffer

Small Animal Technician

Jamie joined Chaparral in 2012 as an extern from Kaplan College.  Upon completion of her externship and graduation Jamie became the newest member of our Small Animal Team. Jamie is working on getting her certification and will be taking the test summer of 2014.  During her off time Jamie enjoys spending time with her handsome Arabian gelding Ulama.

  Tianah Carrillo

              Small Animal Technician


Tiffany Ackerman

Small Animal Technician

Tiffany is a native of Arizona. She loves spending time with her husband, 2 boys and 2 dogs. She started at chaparral back in 2007 and left at the end of 2008 to be a full time mom. In 2011 she welcomed her second son. Recently she came back to chaparral to once again join the small animal team. 


Brooke Taranton

Equine Lead Technician

Brooke came back to Chaparral in October 2008. She was born in San Diego, CA. Brooke really enjoys working with mares and foals. She has four horses, Boss, Taz, Ty, and Indio, and two dogs, Sierra and Maui.

Krista Dupree
Equine Technician

Krista is also a Arizona Native who had a passion for horses as long as she can remember.  Krista is married to her best friend Jake.  Their family consist of 3 dogs, Archer, Gambit and Zero also a rabbit named CiCi who are all rescued.  Which brings up another passion of Krista's, every year she heads the Holiday Festival hosted by Tranquility Trail Animal Sanctuary which is held on the first weekend in December at West World.  Krista has been a CVMC family member for just over 3 years and is one of our three Equine Anesthesia Technicians.

Janelle Baxter

Equine Technician

                                                                  Amy Goda-Dieguez

                                                                   Equine Technician

                                                                   Cheyann Demoney

                                                                   Practice Representative

Secorra Denny

Equine Assistant

Secorra is a student at Arizona Agribusiness and Equine Center - Paradise Valley campus. She has been riding horses since she was 7 years old, now competing in junior rodeo circuits. Another passion of hers is FFA, which she is a chapter officer of. Also, she is a member of her high school's NHS chapter. She plans to go to school to become an equine veterinarian.


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Chaparral Veterinary Medical Center
32100 N. Cave Creek Rd.
Cave Creek, AZ 85331
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