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 training a year ago with a local trainer on my farm, he continued to have a strong will. Although a bit on the aggressive side, he had no dangerous tendencies. Later I switched trainers, moving the horse to the trainer's place. The new trainer's technique was very intensive, and within six weeks the horse became a wild beast--extremely aggressive, attempting to kick and bite, knocking the rider down, and not allowing anybody to saddle him without restraint or even allowing me near him. The most amazing thing was that he would bite himself until he bled. I assumed the trainer mistreated him, so I took him back to my farm and began slowly handling the horse until he was calm. After months of training, he calmed down significantly, and again I started saddle and bit training very successfully until 2 1/2 months ago.

I took the horse to a friend's farm in order to continue saddle training. The first week the horse was a little bit stressed, but there was no extreme behavior during saddling, handling, or riding. The idea was for the horse to get used to being around other horses in order to be prepared for competition in January 2003.

One week later, there was an incident with my friend's stallion who got loose during grooming and created havoc in the stables. My horse was never in the stallion's way and stayed safely in his stall during the situation, but he went nuts. He seemed to flash back to his bad experience with the trainer that "mistreated" him months ago. He turned dangerously aggressive and to my horror, he started to bite himself again. It was impossible to ride him and a dangerous task to control him and unsaddle him. I decided immediately to castrate him, so the next day, the vet did it.

Given these facts, my question is: Would castration solve or help solve the behavior problem? Is he a dangerous nut case in need of euthanasia? Or is there something else to do for him? Rodolfo

With the facts you so nicely described, all I can say is that castration might or might not help. But you should find that out soon. Depending on the cause of the problem, removal of the source of hormones that drive male sexual and aggressive behavior could make him easier to handle. Sometimes a horse like this will quiet down almost immediately and do very well. However, in other cases the problem behaviors continue. Castration might help with the aggression, but might not improve the self mutilation or difficulty with handling and work under saddle. Let me explain a bit about the current understanding of behavior like this and why castration doesn't always help.

Although aggression, self-biting, and difficulty in handling can be behavioral and tend to be a problem more often in stallions than in mares or geldings, in my experience it's fairly rare for aggression, self mutilation, and difficult handling to come and go as a unit when they are simple "behavior" problems. More often, when those problems come and go as you describe, there is physical discomfort at the root of the behavior change. And the physical discomfort can be set off or exacerbated by stressful training or a stressful event such as you have described. So, when there are sudden extreme changes in a horse's behavior like this, particularly for the situation at your friend's farm in reaction to the stallion catastrophe, it's probably worth considerable effort to identify any sources of physical pain that might be causing the behavior change.

What sort of pain could be involved here? Particularly with the self-biting, examples could include gastric ulcers, any sort of painful pelvic or urinary condition, abdominal discomfort, or with a stallion we always want to check for a testicle that is painful from rotation within the scrotum (twisted cord) or entrapped in the inguinal canal. If it was something related to a testicle, hopefully the problem will be immediately and permanently relieved with removal of the testicles. If it is not, it would be great to have a full diagnostic work-up. The physical cause can sometimes be easy to find, or might take considerable effort. But often if you can find and address a physical cause, the problem behaviors go away quickly.

Another important issue is that, although rare, some horses are intermittently aggressive to the point of being dangerous with no identifiable source of pain. We wonder about brain tumors and other neurological problems that might account for this, but equine neuropathology diagnostics are very limited. It's tough to weigh the danger of injury to people and to the horse itself against continuing to search for a physical cause. In those cases, euthanasia often is the best decision. And sometimes the answer is found post mortem.

There is one more interesting part of your question. You say that you raised your colt like a pet, and hint that you might not do that again. I doubt that overhandling is the root cause of the problems you describe, but it could be a modifying factor. It's difficult to judge just how much of a pet your colt became. But some colts handled very closely as youngsters, such as hand-reared foals, have a cluster of behavior problems as they mature. They become what people describe as human-bonded, spoiled, overhandled, or over-imprinted. In general, they behave toward people as if people were horses. They are often overly friendly and attentive to people, and seem to prefer to be with people than with other horses. With people, they appear bargey, "in your face," or not respectful of your space. They are sometimes described as dull to direction in training. When pushed to "behave," they can become aggressive and pushy, just as they would to a herd mate. So they are quick to rear, nip, or turn their butts to you. Perhaps that is what you term strong-willed.

In my experience, those colts can also "lose it" when they have to submit socially to other horses. I know one hand-reared colt that had been raised in close contact with people and apart from horses. He had many of the classic problems of hand-reared colts, and developed several stereotypies in apparent "frustration" when exposed to other horses, including frantic circling of his stall. On occasion he did bite his flank mildly when exposed to other stallions. That type of problem can be very difficult to overcome.

About the Author

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.

Stay on top of the most recent Horse Health news with FREE weekly newsletters from Learn More

Free Newsletters

Sign up for the latest in:

From our partners