Sue McDonnell, PhD, Certified AAB

Sue M. McDonnell, PhD, is a certified applied animal behaviorist and the founding head of the equine behavior program at the University of Pennsylvania's School of Veterinary Medicine. She is also the author of numerous books and articles about horse behavior and management.

Articles by Sue McDonnell

Eating Poop

Our first foal is 10 days old and has already been spotted eating manure. We have accepted the fact that eating manure is normal foal behavior and are trying to ignore it. A quick question: When should he get over this behavior? via e-mail Read More

Barn Aversion

 Our elderly Connemara gelding was unfortunately exposed in his stable to multiple bee stings on more than one occasion over a period of two weeks before the problem was figured out and fixed. He used to be very calm and content in the stable, Read More

A Stallion as a Problem Breeder

We purchased a stallion for breeding at nine years of age. He had bred before, but curiously had very few offspring for his impeccable credentials. He was a lovely stallion, very well-behaved, and a perfect gentleman to work around. When we Read More

Finding a Stallion Handler

We have expanded our semen collection/shipping facility, so we can now keep up to eight stallions in residence and accommodate local stallions trailering in just for semen collection as needed through the season. In the past we have depended upo Read More

Is My Horse Psychotic?

I bought my gelding as a stallion from a local sulky racetrack a year ago (where he never got out of his stall except for training). He had just turned three and was very excitable, so we had him gelded. After several months, he seemed to calm Read More

Foals of Non-Milking Mares

I have a gorgeous palomino Quarter Horse mare that I would like to breed, but I have a problem. She ran into barbed wire as a yearling and she cannot produce milk as a result of that accident. The man who owned her before bred her twice, and he Read More

History of the Horse

There are many scientists who have studied and theorized about how man and horses came to be together. Read More

Stallion Washing Aversion

My husband and I run a business of shipping semen from a few stallions that we board. We have some started ourselves, and some have started elsewhere. Most of them do really well with our simple collection routine. We bring them to the breeding Read More

Men vs. Women Handlers

Your answer to the question about the fellow with the peculiar method of "dominating stallions" (December 2003, led to a very long Read More

Breeding Your Stallion On Cue

Our stallion has a great pedigree, and we have kept him intact hoping he could eventually become a breeding stallion. We’ve put a lot of effort into getting him to show well enough to be worth breeding. He has always done really well except for Read More

General Social Organization of Equids

Editor's Note: This excerpt is from The Equid Ethogram--A Practical Field Guide to Horse Behavior by Sue McDonnell, PhD. The book is available from Read More

Sleeping Patterns

I think my 11-year-old mare isn't getting enough sleep. My mother and I have seen her start to fall asleep in her paddock and in her stall during the day. Her eyes begin to close, her lower lip hangs loose, and her head slowly lowers. When it Read More

Using the Twitch Properly

I attended a short course on horse behavior at New Bolton Center where you explained how a twitch works and your recommendations for how to use it most effectively. It seemed to make so much sense why sometimes it works and sometimes it doesn't, Read More

Breaking A Young Horse

My husband and I recently broke my 3-year-old mare to ride. The first few times she rode like a dream, then she caught on to the idea that when we catch her, she has to work, and she has gotten a bad attitude. Her new antics include bucking. I'v Read More

Spooking on Trail

I have a 17-year-old Arabian mare. When trail riding, she looks for every opportunity to jump, spook, or take off, especially now that my other horse, her companion, no longer accompanies her. The companion is 30 years old, and due to a recent Read More

Water Crossing

How can I get my horse to cross through water when I'm riding him on trail? He refuses to even get his feet wet.           via e-mail

For horses that are afraid Read More

Taming an Aggressive Foal

We recently were blessed with a healthy filly. However, the breeder we bought the mare from had her due date wrong. She came five weeks before we were expecting her. She was born in the pasture with another mare present. Th Read More


In any of the equine behavior literature that I have read, I am unable to find any description of the sleeping behavior we see in our retired broodmare (17 years old). She has functioned as the watch horse in the small herd she was from, and she Read More

Blind and Restless

My 19-year-old horse is 95% blind, and when he's not eating or sleeping he walks in circles. What can I do to stop or minimize this behavior? via e-mail

You certainly would want to have this horse evaluated by a Read More

Get a Vet!

When I ride my 24-year-old Arabian mare Western, she tends to want to pick up the pace and wants to look around. How can I get her to slow down and stay focused? She gets stiff and starts to limp on her left hind leg when I am riding her. Anothe Read More

Don't Leave Me Alone!

Why do some horses not like having their buddies taken out of their pen when they have to stay in?    Katy

The ancestors of our domestic horses were open plains grazing animals, for whom the strategy Read More

Play Invitation

We have been struggling with a very particular behavior problem with a young colt. From birth, he's been a strong and athletic rascal, and has been "full of himself," with the usual colt behavior tendencies. We have dealt successfully with all Read More

Foals and Geldings

My 12-year-old daughter's 9-year-old Welsh Pony gelding (named Taffy) was moved to a new stable about eight weeks ago. Six weeks after the move, Taffy was introduced to the mares and allowed to graze and socialize with them. Since four of the 16 Read More

Handling a Hostile Broodmare

My mare just had a colt today and I have a concern about it because she is 13 years old and not broken. She had been broken three times prior to me getting her, and she won't come near anyone. My question is: How will I be able to mess with the Read More

Bereavement Leave?

I have two horses in my stable yard. One is a 20-year-old retired ex-chaser gelding and the other is a 12-year-old Arab gelding. They have been together for seven years, six of which were spent living on a small yard with just the two of them an Read More