New Bolton Center
Equine Behavior Program

Our Equine Behavior Program and Laboratory at New Bolton Center has grown from within the Section of Reproductive Studies. Since the early 1980s, the program has had research as its core activity. The program has included involvement in related clinical and teaching in the veterinary school and continuing education programs nationally and internationally.


Contact Us

Sue M. McDonnell, PhD
Email: suemcd@vet.upenn.edu
Phone: 610-444-5800
FAX 610-925-8124

Havemeyer Equine Behavior Lab
Penn Vet/New Bolton Center
382 West Street Road, Kennett Square, PA 19348

Consults, Appointments, and On-Farm Visits

What we offer:

  • Telephone consultations
  • Appointments at our facility
  • On-your-farm visit and/or consultation

General Equine Behavior Problems

  • Weaving
  • Cribbing
  • Pacing
  • Headshaking
  • Developmental Foal Behavior
  • Compliance with Management Procedures
  • Aggression
  • Head-shyness
  • Social Grouping and Separation Problems

Stallion Breeding Behavior Problems

  • Libido
  • Erection
  • Ejaculation
  • Rowdy Behavior
  • Handling Issues
  • Breeding Shed Facilities and Design Related to Behavior
  • Self-mutilation
  • Hyperactive
  • Stereotypes (Weaving, Pacing, Cribbing)

Mare Behavior Problems

  • Mare Foal Interaction Problems
  • Estrus Cycle Related Performance Problems
  • Stallion Like Behavior in Mares


Ongoing research projects include:

About Our Semi-feral Pony Herd

Since 1994, a herd of Shetland-sized ponies have been maintained at New Bolton Center.  The foundation herd consisted of adult domestic pony mares and stallions acquired from local farms and auction and simply turned out together in a system of connected pastures with lush vegetation, natural shade and shelter, and ample natural water.  

These ponies live continuously and breed at pasture under relatively natural social and environmental conditions.  Our research objectives include the detailed longitudinal study of equid physiology, behavior, and well-being under natural and domestic environmental conditions.  This herd has also been a valuable educational resource for equine researchers, veterinarians, veterinary students, graduate and undergraduate students worldwide for observation of normal social organization and behavior.

Perhaps the most striking overall observation is that with modest preventive health care, minimal supplementary feeding in deep winter, and almost no other veterinary care or human intervention, these ponies thrive nutritionally and reproduce prolifically.  Mares are continually fertile, have very little reproductive wastage or difficulty, with no need for veterinary intervention.  

Hoof health remains excellent in most cases with minimal need for hoof trimming or other care.  Lameness and colic are almost non-existent.  Laminitis has not occurred in any case in the 11 years of the project.  We are interested in understanding the factors contributing to their extraordinary good health and fertility compared to similar stock kept under domestic conditions.

Equine Behavior Faculty

Sue McDonnell, Penn Vet, behaviorSue M. McDonnell, PhD
Adjunct Professor
Head, Havemeyer Equine Behavior Laboratory


Dr. Sue McDonnell is a native Pennsylvanian, raised in a dairy farming family in the anthracite coal regions north of Scranton. She holds a 1982 master’s degree in Psychology from West Chester University and a 1985 PhD in Reproductive Physiology and Behavior from the University of Delaware. She completed post doctoral study in clinical veterinary reproduction at the University of Pennsylvania’s New Bolton Center in 1987 and became board certified in Applied Animal Behavior in 1991. She is the founding head of the Equine Behavior Program at the University of Pennsylvania School of Veterinary Medicine, where her work includes clinical, research, and teaching activities focused on horse behavior. Dr. McDonnell includes all types of behavior in her clinical case load, with stallion behavior as an area of particular interest and expertise.

Dr. McDonnell’s research interests include several areas within equine physiology, behavior and welfare. She has also traveled to study equids throughout the world. In addition to laboratory and field studies, she maintains a semi-feral herd of ponies specifically for the study of their physiology and behavior under semi-natural conditions. This affords veterinary and animal behavior students the opportunity for long-term observation of equine social and developmental behavior and for first-hand comparison of horse behavior under free-running and traditional domestic conditions.

Dr. McDonnell is the author of two introductory level books on horse behavior entitled Understanding Horse Behavior, and Understanding Your Horse's Behavior, published by The Blood Horse in their Horse Health Care Library Series, and the recently released catalog of horse behavior, The Equid Ethogram, A Practical Field Guide to Horse Behavior, published by Eclipse Press. Along with Dr. Danny Mills, she co-edited The Domestic Horse: Evolution, Development and Management. Among Dr. McDonnell's honors are The George Stubbs Award given by the American Association of Equine Practitioners for contributions to equine veterinary medicine by a non-veterinarian and a Gold Medal from the Agricultural University of Krakow, Poland, their highest honor for distinguished scientific collaboration.

Behavior Medicine in the News

 Dr. McDonnell Interview from 'The Horse'