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

Reactions to Other Species

This might be a bit off the wall, but I hope you can help. We have had horses here at our farm off and on over the years. Since all of the kids moved out and took their horses a couple of years ago, our barn has been empty. Just recently we Read More

How Smart is He? The Thinking Horse

I am writing a paper in my agricultural ethics class on the treatment of horses, and one of my discussions deals with the equality of horses to humans. My roommate and I were debating if horses have the Read More

Stallion Sexual Behavior: When Is He Mature?

How young is too young to breed a colt? We have a coming 2-year-old who acts like he is ready to breed. We don't have any horses to breed to him, but the question came up for discussion last night among a group of guys. This colt was out Read More

More on Panic Attacks

Readers Respond

August's Behavior column (article #914) sparked heated debate about euthanasia for horses with incurable panic attacks. This month we feature two readers' responses and the author's comments.

It was a Read More

Retraining a Rebellious Colt

We recently had a foal who is now one month old. His mother has always been easy to handle in the cross ties or harness (she is a 20-year-old retired Standardbred), but is not a horse which can be caught easily in the pasture, and she isn't Read More

Unpredictable Fear

I have inherited a mare that no one wants because every once in a while she spooks and bolts, big time, without warning. No one has ever been able to figure out for sure what sets her off. But she can go from normal one second to a serious Read More

One-Horse Property?

I am in the process of relocating from Indiana to Pennsylvania. I planned to move my retired 21-year-old Quarter Horse gelding as soon as I could find a property with enough space to keep him at home. I was shocked to hear my realtor in Read More

Mare Savages Foal

Mares which unpredictably savage a foal in this manner typically savage again if given the opportunity, either with a surviving target foal or with subsequent foals. Read More

Physical or Psychological?

A little over two years ago, we acquired a lovely Irish Draught mare, Colleen, from neighbors who were retiring and selling their place. This mare had been their family pleasure horse for many years. After their kids outgrew her, Colleen Read More

Enjoying Veterinary Visits

In our referral equine behavior practice, we frequently rehabilitate horses perceived to be uncooperative with one or more veterinary procedures such as injections, nasogastric tubing, genital examination, etc. We have found that straightforward Read More

Rushing Out of Trailers

One of our horses has a problem with unloading from a trailer. He bolts out of the back as soon as we start to open the back gate, often before we can undo the butt bar. He has done this since we got him over a year ago. He loads and rides Read More

Water Temperature and Drinking Behavior

A few years ago I read an article describing research done at New Bolton Center on drinking behavior. It said that the research showed that in winter, horses prefer to drink warm water rather than ice cold water, and as a result veterinarian Read More

Bizarre Behavior

We have a new problem with our old family pony. Pokey is a Shetland gelding that we have had since our first of five daughters was five years old. We figured he was about 10 years old in 1978 when we got him, so he is now just over 30. Pokey Read More

Foal Eats Manure

One quick question. What about our foals that eat manure? Why do they do it? I find it completely disgusting. My little filly paws and chows down mouthfuls of fresh, warm poop.


Till Death Do Us Part

How do horses perceive a dead horse? Do they know the deceased is not coming back? Read More

Rolling Along

Dear Dr. McDonnell,

Almost every time I let my horses out of the stalls after feeding them, they roll in the dirt, dust, o Read More

Ground Work

Dear Dr. McDonnell,

I am a 12-year-old girl who recently got a 14-year-old Quarter Horse. She is a doll, but there is just Read More

Teeth Grinding

What does teeth grinding mean? I think there is a horse in our barn that does it sometimes. Read More

Horse Play

I have a report to do for science class on animal behavior (middle school, fifth grade). My teacher, Mr. Brennan, said to pick a favorite animal species and a favorite type of behavior. My favorite animals are wild horses, and my Read More

Pasture Feeding Aggression

My yearling colt came from a place where he was kept with a group of yearlings. All were fed their grain in buckets along a fence line, with the buckets hung on posts. I now have him in with one other yearling, a filly which I got at the sam Read More

Biter Gone Bad

We've been raising a Welsh pony for the kids. At about nine months of age, he started with constant nipping at your arm and the lead shank, kind of playing with you. We read on the Internet that this biting is a "colt thing," and that it Read More

Playful Rearing

We recently received an orphaned colt from a very reputable breeder friend who had neither the time nor facilities to raise the baby. We picked him up when he was five hours old, and he is now three weeks old. Health-wise he is doing fine. H Read More

Terrible or Tolerant? Training Horses for Vet Procedures

One of the most frustrating scenarios for horse owners and veterinarians is the horse that's hard to treat. Read More

Overcoming Obstacles Your Horse Fears

I have been enjoying a new horse for a couple of years. He is just great about everything, except crossing railroad tracks. It's so frustrating. He just will not cross. I have tried getting off and leading him across, even bribing him with Read More

Problem Behaviors in Pastures

I recently purchased a 4-year-old gelding. He is extremely aggressive toward my other gelding in the pasture, and I'm unable to turn them out together. I am able to turn the horse out with my pony mare and pony gelding, but he Read More