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

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

Herd Instincts: Sparring

My horse was seen biting another horse in the throat. They were up on their hind legs supposedly playing when all of a sudden my horse made a very unusual move, according to the witness, and bit the other horse in the throat. The other horse ran an Read More

Keeping Stallions Focused

I'm a veterinary student from the United Kingdom and have been riding with a stud farm veterinarian in America going from place to place. I am trying to figure out the art of handling stallions for breeding. Can you please enlighten me on the Read More

Orphans and Families

I wanted to share with you a horse behavior experience that I had after I lost my best broodmare. "Janet" died overnight on May 30, 2006, at age 22. She looked remarkably great for her age, so we were breeding her back to our stallion. She was Read More

Stallion-like Behaviors

I castrated my gelding at 17 months (November 2005). A veterinarian with 35 years of experience showed me the epididymides. My mare had her first heat cycle in March (2006). He mounted and bred her as if he was a stallion. Every time she is in heat Read More

Gelding Herding Mares

Is it possible to change a horse's aggressive behavior? Specifically, I am wondering if there is any information relating to reinforcement contingencies and transfer of learning from a "human-handled" situation to a free-running setting?

The Read More

Rearing and Flipping

We have a Quarter Horse mare whose mother was a bad flipper in the starting gate. She has two half-brothers that were also bad in the gate. All of these offspring were trained by different individuals. This spring, she had a filly that tried to fli Read More

Personality in Horses

How can you predict adult temperament? There is no established battery of tests of character and temperament for horses yet. Many savvy trainers will take a horse, work with him, and get a good idea. Read More

No Vertical Vision?

I follow Pat Parelli's training methodology. While doing the exercise of desensitizing my horse to a ball, I quickly realized that her focus never followed the ball over her head. If I rolled it at her feet, or played with the ball anywhere belo Read More

Trashing the Place

Why do some defecate onto the walls of the stall, pasting manure onto their tails, hindquarters, and all over Read More

Daily Hoof Washing?

I have heard horses should get their feet washed every day, and that this is called the natural moisturizing cycle for hooves. In the horses you have observed in the wild, do they wet their feet every day? If so, please explain how they do Read More

Savage Stallions

Q: I have worked with many different breeding stallions, including Thoroughbreds and Warmbloods back east, then mostly Arabians and Quarter Horses in Texas. We now have a halter stallion that does something I've never seen Read More

Can Horses Be Carnivorous? (Book Excerpt)

My horse has become carnivorous! She eats roadkill such as dead birds, and now I've discovered her stomping on a live rabbit in her stable. She picked it up in her mouth, bashed it against the stable wall, and ate it. Read More

Horse Learning

In a web site advice column written by a veterinarian, he claimed that if a blacksmith trims or shoes a horse incorrectly so that the horse becomes lame within a couple of weeks of work, the horse will make the connection that the blacksmith was Read More


I have a BS in animal science and am now taking graduate courses in animal behavior while working to save up for vet school. A topic we are discussing in class is comparative cognition in a psychology and neurobiology program. This has to do wit Read More

Sexual Misbehavior Vaccine?

I am looking into ways to settle down a colt that is showing full-blown sexual interest already at a 1 1/2 years of age. He's just too much for us to handle, but we are not ready to geld him. If you try to correct him when he's all excited, he Read More

Cribbing Weanling

I have a client with a foal that was weaned a few days ago, and it has started cribbing. Within only a few hours after it was separated from the mare, it was seen doing something funny that the owners now appreciate was cribbing. Once they Read More

Pony Girthing/Mounting Issues

My 11-year-old daughter is having trouble with her pony nipping at her when she is girthing him, and when she goes to mount without an assistant. He also smacks his tail and pins his ears, almost looking like he might cow-kick at her sometimes. Read More

Semen Collecting from a Blind Stallion

We have a Standardbred stallion that had a minor neurologic episode a few months ago that was never really figured out. He has recovered slowly back to normal, except that he has gone completely blind. He does well at pasture and you would hardl Read More


I'm studying for an MSc in Equine Science and am researching equine behavior. Having studied scientific literature, including your catalog of horse behavior (The Equid Ethogram, A Practical Field Guide to Horse Behavior), I cannot find any Read More

Keeping Horses in Harems

Is it possible to keep a gelding at pasture with a stallion and his harem? Read More

Kicking Problems

My horse constantly kicks his stall, and in the pasture he's very rough with other horses, biting and kicking them. Read More

Deliberate Abuse?

I hope you remember me from psychology graduate school back in the early '80s. Time flies. Anyway, I still have horses and enjoy your contributions on behavior to The Horse magazine and web site. Sometimes I wish I had gone into horse or dog Read More

Transportation Trio: Kicking and Pawing

Why would my horse kick the lorry (van or truck) and paw at the floor, both with company or when alone? Read More

Transportation Trio: Runny Nose and Cough

What suggestions do you have for keeping a horse calm during transport without hay, or reducing the dust in the trailer? Read More