Dr. Mark E. Peterson was awarded a Doctor of Veterinary Medicine degree with High Distinction from the University of Minnesota in 1976, where he graduated as class Valedictorian. After moving to New York City, Mark first completed an internship and medical residency at The Animal Medical Center, the largest animal hospital in the world. He then finished a post-doctoral fellowship in both endocrinology and nuclear medicine at The New York Hospital-Cornell Medical Center; this fellowship was awarded and funded by the National Institutes of Health. He obtained board certification as an Internal Medicine specialist from the American College of Veterinary Internal Medicine in 1981.

Dr. Peterson served as head of endocrinology and nuclear medicine at The Animal Medical Center for over 30 years. In addition, Dr. Peterson has held faculty appointments as Professor of Medicine at the School of Veterinary Medicine at the University of Pennsylvania (1996-2000), Associate Professor of Radiology at the Weill Medical College of Cornell University (1983-2005), and Assistant Professor of Medicine at the New York State College of Veterinary Medicine, Cornell University (1982-1988).

Over the last 34 years, most of Dr. Peterson's research efforts have been directed toward advancing our understanding of naturally-occurring endocrine disorders of the dog and cat, especially hyperthyroidism and diabetes mellitus in cats, and hypothyroidism, diabetes mellitus, Cushing's and Addison's disease in dogs. Dr. Peterson was the first veterinarian to document hyperthyroidism as a disease in cats (1979) and to successfully treat hyperthyroid cats with radioiodine (in 1980).  In addition to hyperthyroidism, Mark was the first person to document a number of "new" diseases in cats, including acromegaly, hypoparathyroidism, insulinoma, and Addison's disease.

He has received several awards in recognition of his clinical research efforts and discoveries, including the Beecham Award for Research Excellence (1985), the Ralston Purina Small Animal Research Award (1987), the Carnation Award for outstanding contributions to feline medicine (1988), the British Small Animal Veterinary Association (BSAVA) Bougelat Award for outstanding contributions to small animal practice (1993), The Daniels Award for excellence in the advancement of knowledge concerning small animal endocrinology (1991-1997, 1999, and 2001), The Excellence in Feline Research Award, presented by the American Veterinary Medical Foundation and sponsored by The Winn Feline Foundation (1997), the Alumni of the Year Award, The Animal Medical Center (1998), and an Award for Outstanding Humanitarian Service from the Bide-A-Wee Association, for more than a quarter century of dedicated research in naturally-occurring endocrine disorders of dogs and cats (2002), and Outstanding Service to Veterinary Medicine Award (Veterinary Medical Association of New York City (2008).

Dr. Peterson has published more than 475 journal articles, book chapters, and research abstracts. With more than 250 teaching presentations to his credit, Dr. Peterson is a frequent speaker at veterinary and medical seminars both in both the United States and abroad.

In 2001, Mark founded Hypurrcat, a radioiodine treatment center for hyperthyroid cats in Bedford Hills, New York, which is located about 35 miles north of New York City.  In 2005, Dr. Peterson founded the Animal Endocrine Clinic in Bedford Hills and moved his Hypurrcat facility into that larger hospital space. He also purchased the nuclear medicine equipment needed to open a nuclear imaging center (Nuclear Imaging for Animals) within the Animal Endocrine Clinic.

In 2009, Dr. Peterson expanded the Animal Endocrine Clinic facilities by opening a second office on the Upper West Side of Manhattan in New York City. He sees endocrine patients in both the Bedford Hills office as well as the New York City clinic.  Of course, both clinics have Hypurrcat facilities for treating hyperthyroid cats with radioiodine.