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

Young Guns

Q: I would like to know at what age a colt could breed a mare. I have a 10-month-old colt that has been in with mares until recently, and I was told he could have bred my mares.


A: There are many Read More

Mare Instinct After Loss

After several years of pasture breeding, we are having our first experience with a stillbirth. Read More

Behavior: Strong Reaction to Strangers

Q: I have a 5-year-old headstrong mare with whom I have a good, solid bond. She works well on the ground and is a dream under saddle for me. She does not like strangers coming into the barn, and she counts my boarder's farrier and Read More

Behavior: Discipline for Kicking and Striking

Q: We have a disagreement in our barn: How do you best handle immediate discipline for a horse that strikes out with both front feet or cow-kicks and knows better (not a young horse)? Those people in our barn who have Western Read More

Horse Behavior: War on Punishment

Question from a reader:

I see the American Veterinary Medical Association (AVMA) has posted a statement from their American Veterinary Society of Animal Behavior (AVSAB) about the use of punishment for behavior Read More

Stubborn or Fearful?

Q: Recently, I was working with a group of veterinary students and a patient. It was a colt that had experienced minimal handling or training for leading before arriving at the hospital. On the way to his stall, he needed to be Read More

Natural Stallion Behavior

Q: I own a Lusitano stallion that has been stabled at the same barn for four years. Within the past four to six months, he has shown increasingly aggressive displays toward two stallions that walk in front of his stall. He kicks an Read More

Training a One-Eyed Horse

Working with visually impaired horses has been mostly with those that lost vision as an adult, after they had been trained. And, in general, the horses I have worked with directly have impressed me with how adaptable they have been with losing vision Read More

Potty Problems

I have a serious problem with my 3-year-old Warmblood filly I recently purchased. I had her extensively vette Read More

Raising a Stud Colt

I have bred my first colt this year and thus far have followed handling practices we have used on our previous two filly foals with great success. We have a beautiful Welsh Section C colt who is unafraid of most things, is very people friendly, wil Read More

Becoming a Behaviorist


Veterinarians and nonveterinarians can pursue this growing field.

What does it require to pursue a career as an animal behavioral consultant? I've heard the question a number of times. Read More

Pawing Problem

Is there a humane method for breaking my 4-year-old Missouri Fox Trotter mare from pawing? Read More

Calming Mother Nature

Q: I have a 7-year-old Quarter Horse mare that is quite "the mare." When she is around the geldings (even if they are in different pastures) and in season, she will put her butt up to the fence and wink (the vulvar lips), etc. She Read More

Crossing Bridges

Q: My horse Dakota is not wanting to cross a wood bridge. I walked him across plywood for about three days and had no trouble. Then I rode back to the bridge, and he wouldn't have anything to do with it. Dakota goes crazy, start Read More

Bad-Asses

Q: Some friends and I were discussing the heightened "territorial" aspects of long-ears (mules and donkeys) vs. horses. While I've had horses that were bred and raised out West that were more protective against "predators" such Read More

Best Breeding Approach

Q: For a horse reproduction project in my equine seminar course, I was trying to find video clips of horses breeding. Well, there were many on YouTube, and it took awhile to find the decent ones. But once I found some that were Read More

Anabolic Steroid Effects

A colleague, Larry Soma, VMD, is an anesthesiologist/pharmacologist who conducts research for the Thoroughbred and Standardbred horse racing commissions in Pennsylvania. Basically, his lab develops and validates testing methods for detection of Read More

Oral Attacks

Q: We have an Arabian who, for some reason, has taken to chewing on the horse trailer when we are at a show. He has never done this before. He started gnawing on the fender. We tied him away from the fender, and he started chewing Read More

Defecation Behavior

Q: Why do some horses at our barn poop in the same place every time, then some others seem to go anywhere?


A: We certainly don't know the full answer, but I can tell you what we do Read More

Smart Mare, Smarter Vet

I am doing some positive reinforcement-based behavior modification for needle shyness in a draft broodmare. This mare is just too big and strong for the old-fashioned restraint methods of working around the problem. She has quite a repertoire of Read More

Unsettled Slumber

My horse might have sleeping problems. I have seen him almost fall over trying to sleep. Is this normal? Read More

Positive Reinforcement

Can you explain the concept of positive reinforcement training? What exactly does it mean? I was recently in New Zealand, where I was with a group that seems "converted" to what they call "all-positive training." It sounds like good old-fashioned Read More

In Living Color

Has it been sorted out whether horses can see in color? Read More

A Late Start

I have a 5-month-old colt that was never halter broken. According to the breeder, it appeared that at one point a halter had been put on him, and the experience was traumatic for him.

Since he came home with me, I have been spending time with Read More

Let Nature Work it Out (Shy Stud Colt)

I desperately need some advice about my new colt. He is a 2½-year-old Gypsy Cob named Geordie. He was raised in a herd, then separated as a yearling colt, and ran with a colt herd until I imported him to Australia. He is naturally gentle and not Read More