We Care For Your Pets

ASSISI VETERINARY HOSPITAL        Call Us: 516-256-0022

Dr. Donna O'Leary is available on an as-needed basis, please contact her directly via email at dolearyhogan@myway.com or on her cell 516.662.8870 if you would like to schedule an appointment with her.

Donna O'Leary, DVM


Erinn Mackey, DVM


Dr. Mackey was born and raised in Atlanta, Georgia. She attended Tuskegee University for her undergraduate work in Biology and Animal Science. She continued her education at Tuskegee University, receiving her doctorate in Veterinary Medicine in 2014. Following graduation, Dr. Mackey moved to Long Island to complete a thirteen-month internship at the Veterinary Medical Center of Long Island in West Islip. This internship concentrated in internal medicine, emergency and critical care, surgery, and neurology. Dr. Mackey finds special interest in dentistry and promoting dental health.

When Dr. Mackey is not working, she enjoys exploring New York City, dining, cooking, hiking, and skiing with friends and family.

Maria has worked in the veterinary field over 20 years. She has been the Office Manager/Head Receptionist at Assisi since the hospital opened in 2007. Maria loves helping clients and their pets. She also currently owns three dogs and two cats: a Pomeranian, a Boston terrier, a Boxer and two Domestic Shorthairs. When Maria is not at work, she is at home spending time with two little girls, and her fianc√©.

Maria Rodriguez

Office Manager


Dr. Chen was raised in Huntington Beach, California. He attended University of California at Berkeley for his undergraduate work and majored in integrated biology. After completing his bachelor's degree, he went on to earn a master's degree in laboratory animal science from Hahnemann University in Philadelphia, PA before attending Ross University School of Veterinary Medicine. Upon completing his education in 2004, Dr. Chen went on to do an internship at Long Island Veterinary Specialty Hospital in Plainview. During his internship, he rotated through emergency, oncology, ophthalmology, dermatology, internal medicine and surgery before going on to practice at a small animal hospital in Halesite, NY before joining us here at Assisi. Dr. Chen enjoys every aspect being a Veterinarian and has a special interest in ophthalmology and surgery. He also practices acupuncture and offers chinese herbal treatments. At home, he has a son named Tyler and a mixed breed dog named Maximus who he rescued from the Island of Saint Kitts. He also enjoys doing home improvements, cooking, and gardening as well as skiing, snowboarding, working out, and playing basketball and softball. Dr. Chen also speaks fluent Mandarin!

Online Reviewer


Online Reviewer


Online Reviewer


Jennifer has been grooming all of my dogs for the last 5 years and I have never had or heard of any problems with her grooming. She is a wonderful groomer and has a big following.

I highly recommend Assisi Veterinary Hospital!  I've known Dr. Guzman over 4 years. He s always been professional and willing to answer all kind of questions. 

Very attentive vets, called me all the time to calm my worries and answer all my questions. Saved my dogs life, end of story.


Dr. Ricarlos Guzman is the founder and owner of Assisi Veterinary Hospital. Born in Brooklyn and raised in Queens, Dr. Guzman is proud to establish a hospital serving Long Island and our neighboring boroughs. After graduating from Florida Southern College and completing his prerequisites at the University of Florida, he continued his education at Tuskegee University School of Veterinary Medicine. While completing his degree, Dr. Guzman participated in multiple externships including one at The Animal Medical Center in New York City. After his graduation from Tuskegee University, Dr. Guzman participated in a fourteen-month internship at the West Palm Beach Veterinary Referral Service. This internship was focused on surgery, internal and emergency medicine. Dr. Guzman also worked as a general practitioner in Long Beach, New York prior to founding Assisi in 2007. Also in 2007, Dr. Guzman received accreditation from the United States Department of Agriculture to perform services in connection with interstate and international animal travel. In addition to being a Veterinarian, Dr. Guzman enjoys spending time with his wife, whom he met in Veterinary School and is also a Veterinarian. 


Ricarlos Guzman, DVM

Owner / Veterinarian

Jackson Chen, DVM, CVA