Meet Our Veterinarians

If you are in the process of finding a veterinarian for your small or large animals, take a moment to meet our remarkable team.

Our Small Animal Veterinarians

Dr. Korosec: Veterinarians in Elkhorn

Dr. Jeffrey Korosec

Dr. Korosec graduated from the University of Wisconsin-Madison School of Veterinary Medicine in 1991. He joined Elkhorn Veterinary Clinic in 1992, becoming a partner in 1999. He entered the veterinary profession knowing that he loved animals and wanted to be capable of helping them. As a veterinarian, he quickly learned how gratifying it is to work with caring, capable staff to help not only pets but their owners as well.

During his time away from the clinic, Dr. Korosec volunteers at the Lakeland Animal Shelter and is on the advisory board for Gateway Technical College Veterinary Sciences Program. In addition to his wife and four children, his family also includes three dogs and four cats. Outside of work, Dr. Korosec enjoys spending time with his family, hiking, bicycling, camping, and seeing the national parks.

Dr. Nikki Preston

Dr. Preston completed her Bachelor of Science degree in biology at Illinois Wesleyan University before graduating from the University of Illinois College of Veterinary Medicine in May 2015. She always loved science and knew that she wanted to have a career in medicine. After contemplating human vs. veterinary medicine, Dr. Preston decided that she couldn’t ignore her love for animals and ultimately chose to become a veterinarian. She finds it rewarding to help owners make the best choices for their pets.

Dr. Preston has a four-legged family member of her own, a Lab mix named Chance. She enjoys traveling abroad, running, biking, and hiking.

Dr. Preston: Veterinarians in Elkhorn
Dr. Stewart: Veterinarians in Elkhorn

Dr. Colleen Stewart

Dr. Stewart completed her undergraduate degree in zoology at the University of California-Davis. In 1994, she graduated from the University of Wisconsin-Madison School of Veterinary Medicine and started working at Elkhorn Veterinary Clinic the following year. She knew since early childhood that she would be a veterinarian; she never thought of doing anything else. Dr. Stewart is dedicated to facilitating the human-animal bond and providing medical help and support for her patients.

Dr. Stewart and her husband have three adult sons, a Saint Bernard named Scolaighe, a cat named Moo, a macaw named Cherry, and many fancy guppies. Her hobbies include cooking for her family and boating on Lake Geneva.

Dr. Ellen Waller

Dr. Waller has always been interested in animals and had pets from an early age. She received her Doctor of Veterinary Medicine degree from the University of Illinois in 1980. She worked in a mixed animal practice and then joined the Peace Corps, where she worked with a cattle cooperative in Africa. Dr. Waller has been in small animal practice in this area since 1993 and joined Elkhorn Veterinary Clinic in December 2007. She has also pursued continuing education in ultrasonography and echocardiography.

For Dr. Waller, the most rewarding aspect of veterinary medicine is having a career that surrounds her with animals and the people who care about them, and that challenges her intellectually. There is always something new to learn.

Dr. Waller and her husband Gianni have a Dalmatian/Coonhound mix named Gemma; three cats named Nora, Trinity, and Tom; and four chickens named Goldie, Layla, Ruby, and Robin. Her hobbies include baking, reading, hiking, and other outdoor activities.

Dr. Waller: Veterinarians in Elkhorn
Dr. Wiegel: Veterinarians in Elkhorn

Dr. Liana Wiegel

Dr. Wiegel wanted to go into veterinary medicine since middle school when she got her first horse (that she still has to this day). She received both her animal science and veterinary degrees from the University of Wisconsin-Madison. After graduating from vet school in 2012, Dr. Wiegel completed a hospital and ambulatory internship at Pilchuck Veterinary Hospital just north of Seattle. She continued to work there as an ambulatory veterinarian until joining Elkhorn Veterinary Clinic in 2017. Her professional interests include equine dentistry, lameness, senior care, and ophthalmology. Dr. Wiegel also particularly enjoys treating alpacas, llamas, and other small ruminants.

She and her husband have three dogs, two goats, two horses, one llama, and a turtle. When not working, she enjoys spending time with her three dogs and pony, running, and cross-country skiing.

Our Equine and Large Animal Veterinarians

Dr. Robert Entwistle

Dr. Entwistle, one of the partners in the practice, graduated from the University of Illinois in 1981 and joined the Elkhorn Veterinary Clinic shortly after. He grew up on a livestock farm in central Illinois and as a child was very involved in helping to manage the livestock. He also enjoyed the treatment and reproduction aspects of the job, which lead to his goal of becoming a veterinarian.

Dr. Entwistle and his wife Betsy have four daughters and a son. His family also includes two dogs; a Pug named Sophie and a German Shepherd named Veda. His hobbies outside of work include golf, gardening and yard work, and relaxing with the family.

Dr. Entwistle: Veterinarians in Elkhorn
Dr. Burns: Veterinarians in Elkhorn

Dr. Philip Burns

Dr. Burns graduated from Colorado State University in 1986, and he completed an internship at Naperville Equine Hospital in 1987. That same year, he joined Elkhorn Veterinary Clinic and is now one of the clinic’s three partners. Helping his grandmother deliver lambs when he was five years old instilled in him a desire to become a veterinarian. Dr. Burns became more involved with horses through his experiences in riding and many jobs through college where he worked around horses all the time, mucking out stalls, running a boarding stable, and spending his summers volunteering for an equine practitioner.

Dr. Burns’ special interests include equine reproduction, lameness, and dentistry, which he also practices abroad seasonally in an equine specialty practice in New Zealand. He and his wife and their two daughters reside in Eagle, WI on a small hobby farm with three horses and a cat. Outside of work, Dr. Burns enjoys running, gardening, hiking, fishing, and just being in nature.

Dr. Tracy Busalacchi

Dr. Busalacchi (Dr. Tracy to her clients) decided at four years old that she was going to be a veterinarian. She graduated from the University of Minnesota School of Veterinary Medicine in 1997 and joined the staff at Elkhorn Veterinary Clinic in 2000. Dr. Busalacchi’s many memberships include organizations such as AVMA, WVMA, AAEP, MVMA, and AERC. She is deeply involved with horses, especially endurance riding, and has membership in the AQHA, APHA, and AHA. Dr. Tracy’s specific areas of interest include veterinary spinal manipulation therapy (she obtained certification from the Healing Oasis & Wellness Center), reproduction, emergency medicine, internal medicine, and sports medicine. She also completed the Advanced Functional Neurology Program at the Healing Oasis & Wellness Center.

Dr. Tracy and her husband have a twin son and daughter, five horses, six cats (including barn cats), two dogs, four fish, and seven chickens.

Dr. Busalacchi: Veterinarians in Elkhorn
Dr. Slamka: Veterinarians in Elkhorn

Dr. Megan Slamka

Dr. Slamka grew up on a hobby farm with all kinds of animals. Showing horses and spending so much time around animals cultivated her interest in veterinary medicine. While studying for her undergraduate degree at the University of Wisconsin-Stevens Point, she became fascinated with the biology involved in practicing medicine. Merging her love for animals and passion for horses with her interest in medicine made a career in veterinary practice the perfect fit. The most rewarding part of Dr. Slamka’s career is helping people care for their animals in both the best and worst times. She understands the bond owners have with their horses and pets, so it’s a privilege for her to be a part of that relationship.

Dr. Slamka and her husband Greg have a son named Bodie and a daughter named Olivia. Their four-legged family members include Jake and Jessie, German Shorthair Pointers; three domestic shorthair cats named Jordy, Stevie, and Madison; and three horses, Jazz (Arabian), Udo (Warmblood), and Impact, a National Show Horse. Outside of work, Dr. Slamka’s hobbies include horseback riding, being with her children, downhill skiing, boating, and camping.

Dr. Ashley Slater

Dr. Ashley Slater grew up in rural Oklahoma on a farm with horses and beef cattle. She started showing horses in the English discipline when she was young as well as showing cattle in FFA.

Dr. Slater studied Animal Science at the University of Arkansas. She received her D.V.M. from Oklahoma State University Center for Veterinary Health Sciences in 2018. She then went on to complete a one year rotating equine internship in surgery, medicine, and sports medicine at Brazos Valley Equine Hospitals in Salado, Texas.

Dr. Slater joined the Elkhorn Veterinary Clinic team in October of 2019. Her primary interests include equine lameness, medicine, and wellness. In Dr. Slater’s free time, she enjoys spending time with her two cats, Boots and Yogi, riding her horses and hiking.

Dr. Ashley Slater