How Can I Tell if My Horse is Stressed?

How Can I Tell if My Horse is Stressed?

Behavioral signs of stress might include unwillingness to work, decreased appetite, flightiness, depression, or some other change in a horse's usual demeanor.

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Q. What are the signs that my horse is stressed?

A. The word "stress" is a toughie for me, because it’s used so commonly for all sorts of conditions in horses (and people). If I'm really trying to identify stress, I like to break it down into signs and causal factors that can we can objectively identify, measure, and control.

Stress is actually a normal, adaptive response in an animal to cope with any kind of challenge from the environment. In a horse examples of such a challenge include a big change in training or management, parturition (birth), severe weather, or a strange dog in the pasture. Over the short term, we see increased heart rate, sweating, alarm or alertness, and locomotory behaviors (e.g., moving toward shelter or running) appropriate to deal with the stressor.

Fortunately for us, the domestic horse is an adaptable animal and habituates well to stressors that have a certain amount of similarity and predictability. For example, think of how well horses can adapt to all kinds of traffic noises next to their pasture.

Different signs of stress are seen when a horse is not coping well with an ongoing challenge. Many of our management schemes that prevent horses from doing all their natural behaviors could even cause chronic stress. Behavioral signs might include unwillingness to work, decreased appetite, flightiness, depression, or some other change in a horse's usual demeanor.

As I suggested earlier, if you think your horse is "stressed," first try to identify the specific signs you are seeing. Then consider all the management factors that may cause stress. For example, you might identify in your horse a long-term decreased appetite. If your horse is a high level athlete, he may be confined to a stall much of the day, asked to do intense or intricate training, and fed a large amount of concentrate feeds. He may be transported around a good bit and might receive anti-inflammatory medications. These types of horses often have gastric ulcers, which are known to be caused by any one of these listed factors. Gastric ulcers are a very common cause of poor appetite in our horse athletes. So here, you can identify what you call stress as poor appetite, the immediate cause (ulcers), and also the potential underlying management factors.

Stereotypies such as cribbing, weaving, and stall walking are often considered signs of stress, but they are more complicated than that. When a horse develops a stereotypy, it's generally initiated by some less than ideal management factor, such as confinement, lack of social stimulation, or high-concentrate feeding. However, once initiated stereotypies can be very difficult to eliminate. Because they cause endorphin release they can be "self-rewarding" and thus maintained even with current ideal management.

Stress is often quantified in a research setting by looking at a horse's cortisol levels. Cortisol is a natural stress hormone in animals. Baseline cortisol naturally varies throughout the day. There might be a rise in cortisol simply due to the stress of handling the horse for sampling. Long-term stress might cause not only chronic elevation, but sometimes chronic suppression of cortisol in the system. These variables make using cortisol as a measure of "stress" not particularly useful in practice.

About the Author

Nancy Diehl, VMD, MS

Prior to attending veterinary school, Dr. Nancy Diehl completed a master’s degree in animal science while studying stallion sexual behavior. Later, she completed a residency in large animal internal medicine at the University of Pennsylvania’s New Bolton Center and worked in equine practices in Missouri and Pennsylvania. Diehl also spent six years on faculty at Penn State, where she taught equine science and behavior courses and advised graduate students completing equine behavior research. Additionally, Diehl has co-authored scientific papers on stallion behavior, early intensive handling of foals, and feral horse contraception. Currently she is a practicing veterinarian in central Pennsylvania.

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