Meet The Team

Roberto J. Marchan, DVM

Roberto J. Marchan, DVM

Originally from Puerto Rico, Dr. Marchan graduated from the University of Florida with a B.S. in Animal Science and Ross University School of Veterinary Medicine with a Doctorate of Veterinary Medicine. He completed his clinical training at the University of Missouri. Dr. Marchan began his professional career practicing in Westchester County, New York and later moved to California with his wife who began her veterinary surgical residency program. Dr. Marchan spent two years as an emergency veterinarian at VCA All Care in Fountain Valley, California, followed by eight years at VCA Lakewood in Cerritos prior to becoming the owner of Animal Hospital of South Bay. 

Dr. Marchan enjoys treating cats and dogs from young to old. He was trained by the International Veterinary Acupuncture Society. His special interests are internal medicine, endoscopy, acupuncture, and dentistry. 

When not working at the clinic, Dr. Marchan enjoys spending time with his wife, Dr. Denise Bierens, two sons, Liam & Luca, and four pets: , one cat named Pedro and three Chihuahuas named Lola, Bella, and Biggie Smalls. Dr. Marchan enjoys being involved in the local community. Animal Hospital of South Bay is a proud sponsor of the Manhattan Beach Youth Athletics and is also partnered with the local SPCA LA office performing routine surgeries and treating sick, injured, and/or abused animals.

Denise Bierens, DVM

Denise Bierens, DVM

(Practice Limited to Surgery)

Originally from Canada, Dr. Bierens grew up loving dogs, cats, and horses. She was a competitive equine dressage rider traveling all over North America. She also worked as a veterinary assistant at her local veterinary hospital. Dr. Bierens graduated from Washington State University with a B.S. in Animal Science and Ross University School of Veterinary Medicine with a Doctorate of Veterinary Medicine. Dr. Bierens completed her clinical training at the University of Missouri and began her professional career in small animal general practice in New York. Dr. Bierens subsequently moved to Southern California to complete a three year residency in Small Animal Surgery at VCA West LA. Since completing her residency, Dr. Bierens has continued to work at referral surgical centers (VCA West LA, California Animal Hospital, and VCA All Care) as well as in general practice (VCA Lakewood). 

Outside of professional practice, Dr. Bierens enjoys spending time with her husband, Dr. Marchan, two sons, and four pets. She also enjoys playing golf and painting.

Yukari Ohtomo, DVM

Dr. Ohtomo recently joined our team. Bio coming soon.

Stephanie Zinsser, VMD

Dr Zinnser joined our Rolling Hills location last fall.  Dr Zinnser is a University of Pennsylvania graduate.  After completing veterinary school, she then completed a small animal medicine and surgery internship at California Animal Hospital in West LA.  Dr Zinsser is available Monday through Wednesdays at our Rolling Hills location.

Justine Walker, DVM

Dr Walker joined our Rolling Hills team last fall. Dr Walker graduated from the University of Davis. Dr Walker is available Wednesday through Saturday.  Dr Walker is fluent in Japanese.

Sandra Kranz, DVM

Dr Kranz has been a part of Animal Hospital of South Bay for over a year 2 years.  Dr Kranz completed a small animal surgery residency.  Dr Kranz will now be available on Wednesdays, Friday, and Saturdays. Dr Kranz has a special interest in veterinary soft tissue and orthopedic surgery.

Michelle Verdin, Hospital Manager for Lawndale & Rolling Hills

Ms Verdin joined our team last fall after working for a multi-veterinarian practice in management.  Ms Verdin is available Monday, Tuesday, Thursday, and Friday.

Maribel Aguiar,Lead Treatment Technician/Supervisor (Lawndale)

Erika Bonsky,Lead Receptionist (Lawndale)

Juan Figueroa,Treatment Technician (Lawndale)

Marri Wightman,  RVT, Lead Treatment Technician/Supervisor (Rolling Hills)

Victor Gallegos, RVT, Lead Treatment Technician/Supervisor (Rolling Hills and Lawndale)

Robert Mujsce, Treatment Technician (Rolling Hills)

Eduardo Vasquez Jr., Treatment Technician (Rolling Hills)

Maria Angel, Treatment Technician (Rolling Hills)

Did You Know?

We sponsor the Manhattan Beach Youth Athletics and we also partnered with the local SPCA LA office performing routine surgeries and treating sick, injured, and/or abused cases.