Epivara (epi:epic, var:change) is bringing

Epic Change to the way spays and neuters are performed world-wide.

How we treat animals matters. That's why we created EpiFix, a new way to fix animals without painful, risky surgeries. 

Eliminating invasive surgery is always a good thing, but it's the impact that really matters. 

A low-cost single-injection makes it much easier and cheaper for spay/neuter organizations and shelters to fix homeless animals. That means better health, reduced overpopulation, and a happier life for vulnerable cats and dogs worldwide.

Our Mission is to make life easier and better for animals and humans through innovative science and compassionate care.

Rex A. Hess, PhD, is Epivara's Director of Science and Professor Emeritus of Reproductive Biology at the University of Illinois whose cat rings his doorbell during our meetings. He is also a prolific fundraiser. Since 1986 when he completed his post-doc at the EPA, he has raised a whopping $54 million in grants to fund his research. In his more than 30 years at the University of Illinois he has earned a dozen high-profile honors and held several positions on grant-review panels.


Early in his career, he discovered that a fungicide caused testicular atrophy

because it disrupted the function of efferent ductules in the head of the epididymis. He also found that efferent ductules express more estrogen receptor (ESR1) than even the uterus. His expertise in histopathology, electron microscopy, and reproductive toxicology has carried over into his life-long study of male reproductive biology. These efforts led to a more complete understanding of the stages of the seminiferous epithelial cycle and numerous collaborations on the direct effects of gene knockouts in the testis.


In the last four years alone, he has had 22 publications in peer-reviewed journals, solo authored two book chapters, and co-authored four others. For Dr. Hess, this is an ideal retirement.

Rex A. Hess, PhD

Director of Science

Byron Wittenberg, MBA/CPA


Byron Wittenberg is responsible for building Epivara into the thriving, exciting business it is today. Woofie is the recipient of Epivara's coveted 'best beard' award.


Byron got his master’s degree in Accounting at Notre Dame and went on to complete his MBA in Business Administration at Pepperdine University in 2013.


Byron has over 15 years of finance, strategy, operations, and business consulting experience. Before becoming the COO & CFO of Epivara, Byron led the Finance organizations for several private equity backed multi-national corporations, most recently as the Global Vice President of Strategy & Finance with Beeline, Inc. through its divestiture from GTCR to New Mountain Capital. Previous to that, he provided M&A advisory services, including buy-side and sell-side due diligence, with PricewaterhouseCoopers, LLP, as well as audit services with Ernst & Young, LLP. 

Jenny Shima

Director of Marketing & Brand

Jen Shima is the Swiss Army Knife of Marketing and Brand. Rosie is Epivara's Director of Human Happiness. 


In 2011, Jenny founded The Bacon, a startup with a mission of making it possible for people to do what they love on their own terms and bring home the bacon. Jen built The Bacon from the ground up, hiring and directing seven team members and managing all aspects from ideation and fundraising, to implementation and development.


Of all the hats she wore at The Bacon, the one she loved best was Brand and Strategic Marketing, and she’s delighted to put it on once again to help bring Epivara to life. Jen’s experience as a scrappy entrepreneur brings a valuable dimension to Epivara’s strategic approach and her passion for giving a strong voice to good work keeps her growing.

The Scientific Advisory Board

G. Robert Weedon, DVM, is a feral cat surgeon with TLC PetSnip. He retired in 2018 as a Clinical Assistant Professor of Shelter Medicine at the University of

Indrani Bagchi, PhD, is a Professor and Field Chair in Reproductive Biology at the University of Illinois

Krista Keller, DVM, is an Assistant Professor of Veterinary Medicine at the University of Illinois who specializes in exotic and avian species

Timothy Fan, PhD is a professor of Veterinary Clinical Medicine and serves as the principal investigator of the Comparative Oncology Research Laboratory.

Misung Jo, PhD is a professor of Obstetrics and Gynecology at the University of Kentucky. Her primary research focus is understanding ovarian physiology and the periovulatory process.

Patrick Lin, MS, is a Senior Veterinary Research Analyst specialized in reproductive biology at the University of Illinois

Dr. Jay Ko is the Founder of Epivara and a Professor in the College of Veterinary Medicine at the University of Illinois. His dog Lenny is actually in charge.


Dr. Ko is a life-long animal lover who grew up on his parents' farm in South Korea. He attended Seoul National University (SNU) and taught Biology to middle school students before he went back to SNU for graduate school.  He graduated with a PhD in Developmental Biology in 1998 and did two post-docs at the University of Kentucky in the fields of reproductive biology and chemistry.


At the University of Kentucky, he took a faculty position in 2002, and taught human reproductive biology for 9 years until he found a new academic home in the College of Veterinary Medicine at the University of Illinois (UIUC) in 2011. At UIUC, he teaches reproductive biology and gastrointestinal biology to veterinary and graduate students. He also leads a vibrant team of reproductive biologists as a principal investigator (http://vetmed.illinois.edu/kolaboratory/)


His research has led to the publication of over 80 research articles, to his service on multiple NIH grant review panels, and to the receipt of many awards including the Zoetis Award for Veterinary Research Excellence and the Dr. Gordon & Mrs. Kruger Research Excellence Award. It goes without saying that Dr. Ko is a leading world-expert in reproductive biology, and it's that depth of experience and inquiry that led to the invention of EpiFix. 

CheMyong Jay Ko, PhD

Founder & CEO

The Team

We are animal people. Our pants are always covered in fur and we are not embarrassed at all.


Rex A. Hess, PhD

Director of Science

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Hours of Operation

Mon - Fri: 9am - 5pm

Find Us

60 Hazelwood Dr.

Suite 230G

Champaign, IL 61820

©2020 by Epivara