Adds Equine Behavior Expert Adds Equine Behavior Expert

Dr. Nancy Diehl

Nancy Diehl, VMD, MS, has joined’s stable of writers as an equine behavior expert. In this role, Diehl will join The Horse's current behavior expert—certified applied animal behaviorist Sue McDonnell, PhD, Cert. AAB, of the University of Pennsylvania—in fielding audience and reader questions about equine behavior, training, and equitation science.

Her Q&A format horse-behavior articles will post on each Thursday and will be featured in The Horse’s monthly behavior e-newsletter.

Prior to attending veterinary school, Diehl completed a master’s degree in animal science while studying stallion sexual behavior. She later completed a large animal internal medicine residency at the University of Pennsylvania School of Veterinary Medicine’s (Penn Vet) New Bolton Center and worked in equine practices in Missouri and Pennsylvania.

Diehl also spent six years on faculty at Pennsylvania State University, where she taught equine science and behavior courses and advised graduate students completing equine behavior research. Additionally, she has co-authored scientific papers on stallion behavior, early intensive handling of foals, and feral horse contraception. She currently works as a racetrack regulatory veterinarian and lives in central Pennsylvania.

Diehl says she's excited about fielding questions from The Horse’s audience of horse owners, equine professionals, and veterinarians:“This is an opportunity to educate people on horse behavior and revisit work that’s been so important to me in the past.”

McDonnell, the founding head of the equine behavior program at Penn Vet who worked with Diehl during Diehl’s time at New Bolton Center, said, “Dr. Diehl is an equine veterinarian with years of practice experience. Her training and teaching experience, specifically in equine behavior, along with her thoughtful and caring clinical style, not to mention her great sense of humor—I know of no better choice for the job!”

To submit an equine-related behavior question for a possible response from McDonnell and/or Diehl, email

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