Meet Our Staff

Selecting A Specialist, What it Means & Why it is Important

A veterinarian is considered to be a board certified specialist after successfully completing an approved residency program and examination process administered by a particular specialty college.

Having your pet seen by one of our doctors means that the doctor in charge of your pet's care has received extensive training in his particular discipline. Our doctors are considered experts within their field and have knowledge of the most recent advances in diagnostics and therapeutics to aid in the diagnosis and treatment of your pet.


Dr. Michael Lesser - Cardiology / Medical Director / Practice Owner

Dr. Lesser graduated from Tufts University School of Veterinary Medicine in 1987. He went on to complete an internship in small animal medicine and surgery; and a residency in veterinary cardiology at the Animal Medical Center in New York. Upon completion of his residency Dr. Lesser took over as head of the clinical cardiology service until 1991.

In 1991, Dr. Lesser moved to Southern California. Shortly thereafter, he achieved Diplomate status in the American College of Veterinary Medicine (ACVIM) in the specialty of Cardiology and continued to grow his private cardiology referral practice. In 1998, Dr. Lesser and his wife Dr. Bonnie McGarr, also a veterinarian, established Advanced Veterinary Care Center (AVCC). Over the years, what began as a cardiology specialty practice developed into a full service, multi-specialty referral and emergency hospital. AVCC now offers veterinary specialty services in cardiology, internal medicine, surgery, oncology, acupuncture and chiropractic care. Dr. Lesser is AVCC's medical director and head cardiologist. As a board certified cardiologist, Dr. Lesser's expertise includes non-invasive techniques such as echocardiography, color flow Doppler ultrasound, electrocardiography and non-invasive blood pressure monitoring. Dr. Lesser also performs interventional cardiology including pacemaker implantation, balloon valvuloplasty, angiography and coil occlusion for patent ductus arteriosus.

Dr. Lesser's philosophy is to help provide animals with a good quality of life for as long as possible. This is best achieved when there is a team effort which includes the owner, referring veterinarian and Dr. Lesser all working together to achieve a common goal.


Dr. Sarah Zimmerman - Cardiology

Dr. Zimmerman came to Advanced Veterinary Care Center from Colorado State University. While completing her residency at CSU, Sarah acquired expertise in the cardioversion of dogs with certain arrhythmias. She also participated in the premier veterinary cardiac surgery program at CSU. In July 2006, she successfully completed all requirements of the American College of Veterinary Internal Medicine (ACVIM) and became a Board Certified Veterinary Cardiologist.

Dr. Zimmerman, her husband, and their two dogs and cats reside in the South Bay. She enjoys running with her dogs and living near the beach.


Dr. Danielle Yuhas - Cardiology

Danielle Yuhas earned her DVM from The Ohio State University College of Veterinary Medicine in 2005. Dr. Yuhas completed two (2) one year internships: the first in small animal medicine, surgery and critical care services from the Animal Medical Center in New York and the second in cardiology at Florida Veterinary Specialists, Tampa, Florida. In July 2007, Dr. Yuhas was accepted into Advanced Veterinary Care Center's 3-year small animal Veterinary Cardiology Residency Program and completed her residency in July 2010. Subsequently, in the same month and year, she passed her cardiology board certification exam and became a Board Certified Cardiologist by the American College of Veterinary Internal Medicine (ACVIM).

Dr. Yuhas enjoys traveling and photography. Dr. Yuhas and her husband reside in Manhattan Beach with their three dogs.

Dr-Mari Waterman

Dr. Mari Waterman - Practice Limited to Cardiology

Mari Waterman has wanted to be a veterinarian since childhood. She received her veterinary degree from Cornell University College of Veterinary Medicine in 2007. After graduation, she completed 2 consecutive internships: a rotating small animal internship at VCA Veterinary Specialty Center of Seattle and a cardiology specialty internship at Animal Surgical and Emergency Center in Los Angeles. She trained in cardiology as a resident at Virginia-Maryland Regional College of Veterinary Medicine in Blacksburg, Virginia from 2010-2013. Advanced Veterinary Care Center has welcomed her to the cardiology department starting September 2013 and she is enjoying the warmth of Southern California.

Dr. Waterman works hard to provide exceptional cardiovascular disease diagnosis, management, and client education in both the Lawndale and San Fernando Valley locations. When not working, she enjoys baking, hiking, and spending time with her husband and animals at home.


Dr. Dani Kobayashi - Internal Medicine

Dr. Kobayashi is a 1985 graduate of the UC Davis School of Veterinary Medicine and completed a rotating internship and a residency in internal medicine at the Animal Medical Center in New York City in 1988. She spent four years at Rowley Memorial Animal Hospital in Springfield, Massachusetts and subsequently served as ../staff internist at a large referral center in Fountain Valley, CA until 1995. She became board certified in internal medicine in 1994. From 1995 to 1998, Dr. Kobayashi served as an internal medicine consultant for a regional veterinary laboratory. Her special interests include complex cases in endocrinology, hematology, nephrology and gastroenterology, as well as interventional ultrasound and endoscopy.

Dr. Kobayashi is a native Californian who was born and raised in the South Bay. She completed her undergraduate degree from UCLA. She owns one cat and one dog, and is an avid music and basketball (collegiate and professional) fan.


Dr. Carolyn Briggs - Internal Medicine

Dr Briggs received her veterinary degree from the Ontario Veterinary College located in her native Canada. Upon graduation, Dr Briggs completed a rotating internship in small animal medicine and surgery at the University of Prince Edward Island. Dr Briggs practiced in a small private animal hospital in Washington, before relocating to California to complete a residency in small animal internal medicine at the University of California Davis. Her research work and publications during her residency mainly involved investigation into various aspects of diabetes mellitus in dogs and cats. Dr Briggs became a Board Certified Diplomate of the American College of Veterinary Internal Medicine (ACVIM) in 2000, and has been practicing in Southern California ever since.

Dr Briggs enjoys all aspects of internal medicine, including endocrinology, immunology, gastroenterology, hematology, infectious diseases, nephrology/urology and respiratory disease. Dr Briggs has been trained to perform various endoscopic procedures, including esophagoscopy, gastroduodenoscopy, colonoscopy, bronchoscopy, rhinoscopy and cystoscopy. She also has obtained additional training in tracheal stent placement. Dr Briggs lives in Orange County with her family, her Bulldog Lola, and her cat Tommy.


Dr. Cynthia Panek - Internal Medicine

Dr. Cynthia Panek was born and raised in central Minnesota. She attended the College of Saint Benedict where she completed a B.A. in Biology. She obtained her DVM from the University of Minnesota, College of Veterinary Medicine in 2007.

After completing her DVM, Dr. Panek moved to Northern California's east bay, where she completed her Small Animal Internship and Internal Medicine Residency at Bay Area Veterinary Specialists (BAVS).

Dr. Panek joined the staff at Advanced Veterinary Care Center in December of 2010. Dr. Panek's experience working at Northern California's largest multi-specialty veterinary referral and emergency hospital makes her uniquely qualified to work at AVCC. She works closely with Drs. Kobayashi and Briggs to meet the internal medicine needs of our referring veterinarians and pet owners. In July 2013, Dr Panek completed all the requirements of the American College of Veterinary Internal Medicine (ACVIM) to become board certified in Internal medicine.

Dr. Panek has special interests in gastroenterology, renal disease, immune mediated disease and performing various endoscopic procedures. In her spare time, Dr. Panek enjoys beach volleyball, outdoor activities and spending time with her dog Bodhi and cat Pip Squeak.


Dr. Tammy Da Costa Gomez - Surgery

Dr. Tammy Da Costa Gomez is a 2000 graduate of The Ohio State University College of Veterinary Medicine. After a rotating internship at VCA Berwyn/Franklin Park Animal Hospitals in Chicago, she completed a 3 year residency in small animal surgery at the University of Wisconsin at Madison. She practiced in Chicago for 5 years, during which time she became a Diplomate of the American College of Veterinary Surgeons (ACVS). She joined Advanced Veterinary Care Center in 2010.

Dr. Da Costa Gomez enjoys both soft tissue and orthopedic surgery with a special interest in reconstructive surgery and minimally invasive techniques. She is certified to perform Penn HIP radiographs and stem cell therapy and has had additional training in microvascular techniques. Using cutting edge medicine and multimodal pain management techniques, her goal is to work as an advocate for her patients and help their owners determine the best course of treatment for them and their loved ones.

When not taking care of her patients or her many pets at home, she enjoys time outdoors, wildlife rehabilitation, international travel, and scuba diving.


Dr. Joann Boyer - Acupuncture & Herbal Medicine

Dr. Boyer graduated from the Virginia-Maryland Regional College of Veterinary Medicine in 1989 and came to Hermosa Beach, CA for a one year internship. She practiced general medicine and surgery until 1999, when she became certified in veterinary acupuncture through the International Veterinary Acupuncture Society. Since 2000, she has specialized in veterinary acupuncture. In 2005, she completed post graduate training in chiropractic for animals, with the final goal of The American Veterinary Chiropractic Association certification.

Dr. Boyer resides in Manhattan Beach, CA with her husband Carl, her Border Collie Shelby and her Belgian Sheepdog Ruby, numerous fish and one bird. Beyond her passion for animal healing, she enjoys running, Porsche racing, agility and scouting flea markets for treasures.


Heather Elliott DVM - Emergency Services

 Dr. Heather Elliott received her Veterinary Degree from Western University of Health Sciences in 2008.  Following graduation, she completed a rotating internship in small animal medicine and surgery at Advanced Veterinary Care Center. After successfully completing her internship with AVCC, she worked for Crossroads Animal Emergency Center in Norwalk, CA.

Dr. Elliott has worked in the animal industry for 13 years. Even though veterinary school was intensely demanding, she was able to work at a busy high specialty practice concurrently.  Her goal is to one day pursue an Emergency and Critical Care Residency.

Dr. Elliott enjoys the unpredictable aspect as well as the fast pace of emergency medicine.  Her philosophy is to provide compassionate care to clients and patients, especially during stressful emergency situations.


Alba Rocio Ramirez DVM - Emergency Services

Dr. Rocio Ramirez earned her veterinary degree from the University of La Salle in her native Colombia.  After completing her DVM, Dr. Ramirez moved to the United States where she worked both as a surgery technician as well as Intensive Care Unit & Emergency Critical Care manager at a referral veterinary clinic. 

In 2010, she successfully completed a rotating internship in small animal medicine and surgery at Advanced Veterinary Care Center and thereafter, continued at AVCC as an Emergency Practitioner.

Dr. Ramirez is very interested in Internal Medicine and plans to begin a residency in this specialty within the next few years. Dr. Ramirez lives in the South Bay with her husband and 2 cats.  In her spare time, she enjoys dancing, reading and traveling with her best friend and husband, Walter.


Jim Hemker - Hospital Administrator

Jim's expertise includes strong administrative, operational and leadership skills. His 25+ years of experience in the field of Health Care Administration helps to insure that we manage our practice to deliver unsurpassed veterinary specialty care, providing our patients with a wide range of diagnostic and therapeutic options for their special needs. His responsibilities include day-to-day operations and practice management.

Jim holds a Master of Science Degree in Health Administration and Bachelor of Science Degree in Health Science from California State University, Northridge and a Bachelor of Art Degree in Life Science from San Jose State University. Jim also completed the American Animal Hospital Association and Purdue University's Veterinary Management Institute's (VMI) series in veterinary practice management.


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