Accessibility View Close toolbar


Our Doctors

Frank Kostolitz

Dr. Frank Kostolitz

Dr. Frank Kostolitz attended the University of Parma in Italy where he received his DVM. He started practicing veterinary medicine in Middletown in 1984, focusing on small animal medicine and surgery, and in 1990 he established Yalesville Veterinary Hospital in Wallingford, CT.

Dr. Kostolitz’s main goal is to strive for only the best in patient care, client communication and satisfaction. He lives in Cheshire with his wife, 3 children, their greyhound, Stella, and their 2 cats.

              Dr. Lisa Saravis

Lisa Saravis

Dr. Lisa Saravis is a Connecticut native. She obtained her Bachelor’s Degree in Biochemistry graduating cum laude from Connecticut College.

She was inducted into the Society of Phi Zeta, the Honor Society of Veterinary Medicine while attending veterinary school and graduated cum laude from the University of Pennsylvania School of Veterinary Medicine in 1994.

Dr. Saravis went on to practice small animal medicine in North Haven for the next eleven years before joining Yalesville Veterinary Hospital. She is the past president of the New Haven County Veterinary Medical Association and enjoys spending her free time with her family, horses and her cat Brownie.

ocallaghanDr. Jill O’Callaghan

Dr. Jill O’Callaghan is a Connecticut native. She grew up in New Canaan, CT and graduated from Wake Forest University in North Carolina with a degree in Biology in 1997.

She then attended Kansas State University where she received her D.V.M. degree in 2002. Upon graduation she worked at a small animal hospital in New London for seven years before joining the Yalesville staff in August 2009.

Her clinical interests include internal medicine, surgery and acupuncture. She is a certified veterinary acupuncturist through the International Veterinary Acupuncture Society.

Dr. O’Callaghan is also an adjunct faculty member at Middlesex Community College, where she teaches part-time in the veterinary technology program. She lives in Guilford with her husband, children and a dog named Charlie.


Dr. Robert Hallock

Dr. Robert Hallock is a 1969 graduate of the University of Pennsylvania School of Veterinary Medicine. He was the owner of Meriden-Wallingford Veterinary Associates from 1971 until 2014 when both hospitals merged. We are thrilled to have him on our staff!

Dr. Hallock has served on the board of directors for the Fidelco Guide Dog Federation as well as serving as their staff veterinarian. He has also been very active in Retriever Field Trials – having bred, trained and competed with his own Labrador, Flat Coated and Curly Coated Retrievers.

Dr. Hallock was also on the executive board of the Connecticut Veterinary Medical Association for 8 years. Currently he is a member of the Connecticut Veterinary Medical Association, the New Haven County Veterinary Medical Association, the American Association of Feline Practitioners and the executive board of the Connecticut Boxer Club.

His current interest is in the breeding of Boxers and competing in Obedience and Conformation events. Over the years, he and his wife have had 13 Champions, two of which were nationally ranked in the top 20.


                                                                                                                                              Dr. Dana Muir-Preston doctor

Catherine Donewald

 Dr. Catherine Donewald