OUR VETERINARY TEAM
"An animal's eyes have the power to speak a great language" ~Martin Buber
Petchester's Veterinarians--"An Eye of a Different Color"
We are proud to tout that our founding veterinarians, Dr. Lester Sills and Dr. Zsach Ben Adi, have not only combined clinical experience of over five decades, but they also have been voted one of the "topVets" in Westchester County, New York and featured in Westchester Magazine three years in a row---2011, 2012, 2013. "topVets" was started with the intent to identify the best veterinarians and specialists in the country and is the only list of its kind chosen by the veterinary professionals themselves. Veterinarians must be voted in strictly by their peers, and virtually every veterinarian is given an opportunity to participate. And because listings are peer chosen and cannot be purchased, inclusion in topVets is considered to be a distinct honor. Also, Petchester was voted Best Veterinary Center by Westchester Magazine in 2023, 2025 and 2026. Another reason that you should be confident that your pet’s care at Petchester Veterinary is in the best of hands.
Our veterinarians are well versed in small animal and exotic medicine and surgery and receive ongoing continuing education to keep them updated on the latest medical concepts and techniques. They are also active in veterinary professional organizations which keeps them further connected to the trends in veterinary medicine. Our veterinarians also believe in giving back to the community and do this by offering their veterinary services to various rescue groups, animal shelters, and nature centers. They have also been available in disaster situations like treating the search and rescue dogs at the World Trade Center site in the aftermath of 9-11 and helping to treat smoke inhalation in animals that were involved in a local, residential, apartment building fire. Our veterinarians are also committed to educating students, clients, and the public and visit schools to give presentations on animal health. They also invite groups to tour the hospital and offer volunteer opportunities for senior internships and school projects. But, most importantly, our veterinarians love animals. That is why they chose this profession. They are committed to ensuring the health, welfare, and well-being of all animals.
Lester Sills, DVM
Veterinarian and Co-founder of Petchester Veterinary
Dr. Lester Sills has been practicing veterinary medicine for 35 years. His Doctorate in Veterinary Medicine (DVM) was obtained in 1988 from The Ohio State University College of Veterinary Medicine. He began practicing small animal medicine in South Windsor, Connecticut for four years and practiced in Scarsdale, New York from 1992-2013. He is one of the co-founders of Petchester Veterinary which opened its doors in December of 2013. His many years as a seasoned clinician and surgeon culminated in his being voted one of the Top Veterinarians ("topVets") in Small Animal Medicine and Surgery in Westchester County and featured in Westchester Magazine in 2011, 2012, and 2013. Petchester was also voted the Best Veterinary Center by Westchester Magazine in 2023, 2025, and 2026. He served as a volunteer, consulting veterinarian and board member for the Greenburgh Nature Center (GNC) treating many different exotic animals for over 20 years. He received the GNC’s Volunteer of the Year Award in 2001. He has a special interest in avian medicine and treats many other exotic pets in addition to birds such as reptiles, rabbits, ferrets, and rodents. He is also well known for his ever-present willingness to accept and treat injured wildlife. Dr. Sills was one of a group of veterinarians that helped treat the rescue dogs at the site of the 9-11 World Trade Center disaster. He has also served on the Board of the Westchester-Rockland Veterinary Medical Association (WRVMA) for twenty five years and was chairman of the Ethics Committee from1999-2022. He is a member of the American Veterinary Medical Association (AVMA) and Association of Avian Veterinarians (AAV). He also continues to volunteer for Bully Baby Rescue and Pet Rescue for their spay and neuter programs. Dr. Sills currently resides in Westchester County, New York with his veterinarian wife, two children, and three rescued dogs. In his spare time, he enjoys yoga, hiking, biking, and walking his dogs.
Zsach Ben Adi, DVM
Veterinarian and Co-founder of Petchester Veterinary
Dr. Zsach Ben Adi was born in Jerusalem, Israel and went to veterinary school in Germany at the Justus Liebig University graduating in 1997. He completed a one year internship and began practicing in Rhinebeck, New York for his first four years. He worked in a small animal clinic in Scarsdale, New York for nine years. Dr. Ben Adi is a co-founder of Petchester Veterinary which opened in December, 2013. He was featured in Westchester Magazine as one of the Top Veterinarians ("topVets") in all of Westchester County, NY in 2011, 2012, and 2013. Petcheter was voted Best Veterinary Center by Westchester Magazine in 2023, 2025, and 2026. He is a proficient clinician and surgeon and has extensive training in veterinary ultrasonography. Dr. Ben Adi is a member of the Westchester-Rockland Veterinary Medical Association (WRVMA) and American Veterinary Medical Association (AVMA). He also continues to volunteer his time and expertise to the spay and neuter programs of New York’s Pet Rescue. Prior to his veterinary medical career, Dr. Ben Adi served as a paratrooper in the Israeli Army. After his military service, he traveled through South America for an entire year. It was there, in the Galapagos Islands, where he met his wife who is from Langenfeld, Germany. Dr. Ben Adi is fluent in many languages including English, Hebrew, and German and has some basic knowledge of Spanish. Dr. Ben Adi likes to hike and bike as well as has been a coach of a boys’ travel soccer team. Dr. Ben Adi has two children, two dogs, and two cats, and lives in Garrison, New York.
Associate Veterinarian
Dr. Victor Koos was raised in Mount Kisco, New York. He had a fondness of animals at a young age and started working as a veterinary assistant in his junior year of high school. Victor received his B.Sc. in Wildlife Science from the SUNY College of Environmental Science and Forestry in 2012. He then worked as a field ornithologist on conservation and research projects with The University of Melbourne, The U.S. Fish and Wildlife Service, The Institute for Bird Populations, and the CNMI Division of Fish and Wildlife. Victor transitioned back into veterinary medicine in 2014, working as a veterinary technician in Manhattan until applying to vet school. Dr. Koos graduated from the Cornell University College of Veterinary Medicine in 2021 and then moved to Brooklyn in order to practice as a primary care veterinarian for dogs and cats in New York City. Victor has now returned to Westchester County and is excited to join the Petchester team! His professional interests include preventative care, dentistry and oral surgery, internal medicine, dermatology, and soft tissue surgery. Dr. Koos is a member of the American Veterinary Medical Association (AVMA) and Westchester Rockland Veterinary Medical Association (WRVMA). He has a Border Collie mix named Xander and a senior orange cat named Orenthal. In his spare time he likes playing fetch with and walking his dog, cycling, fishing, birdwatching, photography, and cooking.
Victor Koos, DVM
Associate Veterinarian
Noah Russo was born and raised in Westchester, New York and is excited to be returning home to join the team at Petchester Veterinary. He first became part of the Petchester family years ago, working as both a veterinary assistant and receptionist while completing his studies. Dr. Russo completed his undergraduate degree in Animal Science at Cornell University’s College of Agriculture and Life Sciences, where he was accepted into an accelerated 7-year BS/DVM program. He went on to earn his Doctor of Veterinary Medicine from Cornell University College of Veterinary Medicine, graduating in May 2025. During veterinary school, Dr. Russo volunteered with a pet loss support hotline and participated in spay and neuter clinics both locally in Tompkins County and internationally in Guatemala and the Dominican Republic. His professional interests include preventive medicine and client education, internal medicine, surgery, and end-of-life care. His species of interest include dogs, cats, and ferrets. Outside of work, Dr. Russo enjoys spending time outdoors hiking, playing pickleball, and rollerblading. He also has a love for fitness and enjoys working out at the gym. He shares his home with his two dogs, Kali and Chloe, and his two ferrets, Korra and Guber.
Noah Russo, DVM
Emily Zimmerman, DVM
Associate Veterinarian
Dr. Emily Zimmerman joined the Petchester Veterinary team in 2026. Born and raised in downtown Manhattan, Emily developed a love for animals growing up alongside her high-spirited Wheaten Terrier, Honeybun. When Honeybun was diagnosed with cancer and underwent a leg amputation, she went on to enjoy seven more wonderful years of life, an experience that helped inspire Emily’s interest in veterinary medicine. Emily received her undergraduate degree from Tufts University, where she double majored in Clinical Psychology and Child Studies. She then earned her Doctorate of Veterinary Medicine from The Ohio State University College of Veterinary Medicine, graduating in May 2026. During veterinary school, Emily worked with Columbus Humane, where she gained hands-on experience in high-quality spay and neuter surgery. The experience fostered a particular interest in spay and neuter surgery and a passion for the important role it plays in animal welfare and community veterinary medicine. Dr. Zimmerman’s professional interests include preventative care, internal medicine, and client communication. She particularly enjoys building long-term relationships with her patients and their families and believes strongly in the partnership between veterinarian and pet owner. She values working collaboratively with owners to develop individualized care plans that support their pets’ health and quality of life. Emily shares her home with a feisty Green-cheeked Conure named Mimi. Outside of the clinic, she enjoys biking, watercolor painting, and exploring Manhattan’s many great restaurants.