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

Sleep-Crashing

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

Hauling Training

I'd like recommendations for safe hauling for weanlings. What's the easiest way to proceed for happy hauling? Read More

Sudden-Onset Headshaking

My pony started tossing his head and cribbing at about the same time. The head tossing has increased to the point of not being able to ride him. He has had his teeth floated and has been checked by a vet for common problems. He has never had Read More

Fear of Cows

My horse is a 16.3-hand 7-year-old off-track Thoroughbred. His history is largely unknown. My problem is that in the five months I've had him at a boarding stable, he hasn't gotten over his fear of cows and their field, which is about 10 fee Read More

Tail Rubbing

One of our mares rubs her butt on everything, all the time. It messes up the top of her tail, and she always has these big scratch marks across her butt.

We can't seem to get her to stop it. We have dewormed her regularly and Read More

Abusive Training for Stud Colts

I hope you are not offended by this question, and that you will find time to answer it if you know anything about it or maybe could refer me to someone else who might have heard of this fairly unusual advice. My boyfriend was afraid to write Read More

Picking a Children's Pony

One of the fondest memories I have as a very young child is hugging and brushing a pony that our neighbors had, and I had always wanted to have one of my own. Our daughter is 3 1/2 years old and we are expecting our second child, a boy, in Read More

Tough Catches

I have an 18-year-old Tennessee Walking Horse that was vaccinated two weeks ago with no apparent reaction. A w Read More

Understanding Male Aggression

I purchased my horse a year ago knowing he had some aggression problems. He is great around people, just not around other horses. Unfortunately, when he attacks, he goes for the throat just behind the jaw line. He refuses to let go at times, Read More

Can't He Just Drink Out of It?

There are several possible explanations as to why a horse might play with his water bucket every night. Read More

Slow-Starting Stallion

We just started using a 3-year-old Quarter Horse stallion for breeding. He is sort of interested and will rub his head on the mare a bit, but he drops about half-way, then up, down, up, down. He doesn't seem shy or anxious, just lazy, like a Read More

Follow-Up: Carnivorous Horses

Last October, we shared letters from three readers describing horses killing and/or eating small mammals and birds (see "Carnivous Horses," article #3832 at Read More

Kicking Out at Feeding Time

My gelding is stall kicking. I'm not there at feeding time, but my trainer tells me the stall kicking occurs when it's feeding time. The same thing happened the last two places he lived. She has tried feeding him first, but that didn't help. Read More

Trailer Resistance

I've had my yearling filly all of her life. I trained her from week one to trailer load, and she was fine with getting in and out. However, this was with a four-horse slant load trailer that steps up. Now I need to load her into a two-horse Read More

Foot Work: Training for Hoof Care

My only horse finally lived out his days with me last fall. He died peacefully at the great old age of 32 years. He had been with me through thick and thin for 21 years, and was a sweetheart of a horse. He came to me completely broke and was Read More

Clusters of Aggression Problems

I have an almost 4-year-old Peruvian stallion, born and raised on my farm, living with only his mother and a sister. Because of my inexperience, I treated him as a pet. Since a very young age, he showed a strong will. When I started saddle Read More

Keeping a Stallion With a Foaling Mare, or Mares

We have a mare and stallion together in a pasture. We borrowed a stallion in August just to breed this mare. They have been together since then, and we just had the mare checked for the first time since they were together and found out that Read More

Fly Masks

When I am bringing fly-masked horses in from the field, I feel insecure, as if it's hard to tell what they are doing. I always feel better when fall comes and the masks come off. I've talked to other people who feel the same way. Do you know Read More