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

Pregnant Personality

I have a 7-year-old Morgan mare who is pregnant for the first time. She was orphaned at foaling but got a nurse mare quickly, and has always been overly friendly and sweet. However, at several months in foal she has become aggressive and nippy. Read More

Odd Posture to Poop

Reader question about why her horse assumes a contorted body position when defecating, and an answer by Sue M. McDonnell, PhD, Certified Applied Animal Behaviorist. Read More

Foaling Among Peers

We have a 20-year-old Paint mare due to foal soon. Her pasturemate is a 15-year-old open mare who has had prev Read More

Empty Leg and an Attitude?

Q:Please help. No matter who we talk to we can't seem to figure out what's going on with my daughter's 14-year-old American Saddlebred gelding. He is losing weight, but he is eating everything in sight, and Read More

Dominance Issues

I have a 2-year-old Fox Trotter gelding that seems to always be in a bad mood. He hardly ever puts his ears f Read More

Gelding Still Acting Like a Stallion

Q: My friend has a 14-year-old gelding who was gelded late (I'm not sure how late, but he did sire some foals) and is pastured with a 23-year-old mare. Last spring they were fine pastured together. This spring, however, Read More

Tongue Troubles

I have a filly who occasionally will stick her tongue out the side and loll it at times when I do ground train Read More

Compulsive Urinating on Hay

Dr. Sue McDonnell works with reader whose horse urinates on his hay as a marking behavior. Read More

Nip Nipping in the Bud

A few of our therapy horses are very mouthy. When they are in session and have a child on their back they try Read More

Earning Back Trust

I have a 15-year-old Thoroughbred gelding, Simon, that I have owned for five years. I need some real advice be Read More

Self-Mutilation or Pain?

I have a horse that I believe is displaying a form of self-mutilating behavior, and I'm wondering if you have Read More

Trailer Loading Methods

Do you recommend a particular method for efficiently helping owners load their horses under these veterinary c Read More

Feet Feud

My horse Lucky has started a behavior problem when we handle his feet. He's always been awesome about lifting Read More

New Herdmates

Dr. Sue McDonnell helps a reader whose horse's attitude changed with his new barn. Read More

To Breed, or Not to Breed?

Do you feel breeding can actually benefit the performance behavior? Read More

Herd Instincts Revisited

(Editor's Note: Dr. McDonnell answered a reader's questions on her horse biting another in the throat in the March 2007 issue. The reader and McDonnell follow up on this interesting Read More

Unbalanced Behavior

Several months ago my gelding started having "tantrums" and displaying stallionlike tendencies and characteris Read More

Can Horses 'Herd' Across a Fence?

I know horses like to "herd" with one another, but how close do horses have to be to feel comfortable? Read More

Anabolic Steroids or Confidence?

How long do the effects of steroids last after they are given to the horse? Read More

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