What is separation anxiety in horses?
More commonly referred to as "barn sour" or "buddy sour", separation anxiety is when an individual experiences extraordinary fear, depression, or panic in response to separation from another individual of high value. Separation anxiety usually appears in horses through increased locomotion (pacing), vocalization, pawing, kicking, rearing, urination, defecation, head shaking, nodding, and tail swishing. It can also cause an elevation in heart rate, adrenalin, noradrenalin, cortisol, and body temperature.
What I would like everyone to understand is that this is not just naughty behavior. Horses have such a strong evolutionary desire to constantly be with another horse, they cannot help but feel endangered when they are taken out alone for a ride or are the only one left behind. Solitary animals like tigers don’t get separation anxiety because they're adequately prepared to survive alone. Horses on the other hand use the “dilution effect” (group living) as a survival mechanism. This works because the more individuals there are in one area, the less likely each one is of becoming a target.
Handlers cannot focus on punishing the behavioral response to separation anxiety (pacing, pawing, vocalizing, etc). This would only be a band-aid fix. Horses with separation anxiety require structured behavior modification in the form of systematic desensitization.
How do we prevent it?
When horses are young, they use their mother for security and safety. They are constantly seeking proximity to them and will become distressed when they are separated. As they mature, a horse will begin to bond with other horses and expand their attachment base. However, weaning practices can have a huge impact on a horse’s likelihood of developing separation anxiety later in life. A 2018 study showed that foals who were weaned by gradually increasing the amount of time spent away from their mothers before moving them into separate pens were less likely to show stress related behaviors than foals who were weaned suddenly. The mares from the second group who were abruptly separated from their foals had higher levels of cortisol, more alert posture, increased vocalization, and restlessness. Foals from the first group were more curious and less fearful than the other foals who had significant behavior differences.
How do we eliminate it?
There are currently no medications available on the market for the treatment of separation anxiety in equine like there are for dogs. Even if there were, it would still be essential to have some kind of behavior modification. These horses require habituation to departure cues as well as systematic desensitization and counterconditioning to planned separation.
Departure cues are events and objects the horse with separation anxiety has associated with being separated from her companion or having her companion taken away. These can include everything from your car pulling up to the barn, having a halter in your hand, bringing your saddle out, to mounting. In order to stop a horse from having a reaction to these stimuli, you have to change the predictability of each of these, otherwise your horse may be over threshold before you even step out of your car. I recommend performing one departure cue at a time until you no longer see a change in behavior. Make sure the horse is at liberty (not restricted by space or a lead rope) when practicing this in order to avoid flooding. Your horse needs to begin in a calm state of mind before moving on to the next cue.
Systematic desensitization is when an individual is exposed to a weaker version of an aversive stimulus in order to increase their tolerance of it. For this part, you can make the stimulus (separation) weaker by reducing exposure time, distance, or breaking it down into smaller components.
Counterconditioning helps by changing an individual’s response to a stimulus by associating the stimulus with one of opposite value. Since the horse left behind is usually the one who gets more upset, it is a good idea to make sure this horse has plenty of enrichment in their area like treat licks or ball feeders. If this horse is particularly bonded with a person, this person could remain with the horse for grooming or liberty training.
In order to begin working with your horse, you have to determine their comfort zone. This is going to be the specific distance in which the companion horse must stay inside of before the horse with separation anxiety begins to exhibit stress signals. In other words, if Horse 1 is the horse with separation anxiety and Horse 2 is the companion, there is a certain distance in which Horse 2 cannot exceed from Horse 1 before Horse 1 begins to display anxious behaviors. When Horse 2 reaches the edge of that comfort zone, Horse 1 will have more alert posture (stops grazing, picks her head up, ears are flicked forward, eyes get big, nostrils are flared). As soon as Horse 2 steps outside of that comfort zone, that is when you will start to see displacement behaviors like increased vocalization, pacing, pawing, rearing, etc. Some horses may be more stoic about their separation anxiety and may only display low levels of displacement behaviors or calming signals like scratching their face on their forearm or turning their head away from you. You never want to try to train outside of the comfort zone because no learning will occur when the horse is already stressed. Instead, you need to start inside of the comfort zone and work on expanding its perimeter.
For example, when I am working with a horse, I stop at the edge of the comfort zone with Horse 2, wait until Horse 1 is relaxed, take 5 steps further, wait until Horse 1 is relaxed again, then take 10 steps back towards Horse 1. I repeat this process several times and simultaneously gradually increase the time spent at the edge of the comfort zone before bringing Horse 2 back into the pen. Keep in mind, when working on the horse who is being led away (if Horse 2 were the one with SA), use a higher rate of reinforcement when moving away from the herd than you do moving back towards the center of the comfort zone.
You’ll also want to pay attention to trigger stacking. This is when multiple stressors or stressful events happen simultaneously or back to back that when combined may cause the individual to go over threshold and display fight or flight behaviors. If you are doing a planned separation, keep an eye out for other stimuli in the environment that may make your horse even more stressed. For example, if you were to take your horse out for a trail ride alone on a windy day, you are adding separation to an overexposure of noise and smell so that when one too many rabbits cross your path, it will cause an insecure horse to bolt home. We cannot just tell our horse they’re being silly and that they need to get over it. Just like with the plastic bag, their fear is real and it is not our job to invalidate that fear but to help them understand that they are safe.
One thing you can also try is adding a safety cue. A safety cue is exactly what it sounds like. It is an object or event that lets a horse know they are going to be safe. This is a cue that is unique to separation and can be easily identified by the horse. This must be different from a departure cue and be used at every planned separation. It needs to only be used when you can guarantee the horse is going to be safe and the separation will be short-lived. A safety cue can include a specific ball feeder/treat ball, an Equll mat, or puzzle box. If the horse gets full-blown separation anxiety after a safety cue is performed, it will poison the cue and render it useless.
As much as we would like our horses to carry on normally when their friend is taken out for a ride, at the end of the day, it is unfair to leave any herd animal completely alone. It is considered a normal behavioral response in a herd animal and this kind of stress-induced relationship is especially common among rescue horses. With this in mind, it may be helpful to house horses in groups of 3 or more that way removing one will still leave the other with a companion. Sometimes separation anxiety is so strong that it interrupts or prevents learning and performance so that it needs to be addressed before anything else.
Take a moment to assess whether or not your horse could benefit from these exercises. Anxious or not, your horse will thank you.
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