Equine Self Mutilation Syndrome in Horses

Equine Self Mutilation Syndrome in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

Most common symptoms


Rated as moderate conditon

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Most common symptoms

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Equine Self Mutilation Syndrome in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

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What is Equine Self Mutilation Syndrome ?

ESMS is much more common in males rather than females. It is most prevalent in stallions, most commonly Arabian, Quarterhorse and American Standardbred stallions. Treatment plans (such as medication or environmental changes) specific to each case will be needed in order to combat this syndrome.

It can be difficult to diagnose equine self mutilation syndrome or ESMS. Many people confuse ESMS with some form of behavioral reaction to colic, skin issues or diseases, epilepsy or hormonal imbalances as all of these have similar symptoms.  Horses suffering from ESMS will bite or nip at their flanks, chest, legs or tail oftentimes drawing blood. This behavior is exhibited daily and sometimes multiple times a day.

Symptoms of Equine Self Mutilation Syndrome in Horses

Your horse will exhibit some alarming behaviors when suffering from ESMS. Contact your veterinarian for a consultation if you notice any strange behaviors or see bite marks on your horse. 

  • Spinning around
  • Kicking hindquarters
  • Bucking
  • Running into fences
  • Throwing themselves against stall walls
  • Throwing themselves to the ground
  • Destroying blankets or other equipment
  • Repeatedly nipping or biting themselves 
  • Extreme agitation

Causes of Equine Self Mutilation Syndrome in Horses

Some researchers suggest that equine self mutilation syndrome may be, in part, hereditary. The sensitivity to stressors that can lead to ESMS can be passed from generation to generation. The actual behavior that causes the horse to self mutilate may develop from a number of things such as stall confinement, boredom, sexual frustration or inactivity. Once the behavior has started and your horse perceives that there was pleasure associated with self mutilating, the behavior will continue.

Diagnosis of Equine Self Mutilation Syndrome in Horses

There are no known tests that can be performed to diagnose equine self mutilation syndrome. Your veterinarian will complete a thorough physical examination of your horse and will observe the behaviors being exhibited. 

Your veterinarian may run tests to rule out other possible causes for the behavior. Once a thorough examination has been done, your veterinarian can conclude from the symptoms present that your horse is suffering from ESMS.


Treatment of Equine Self Mutilation Syndrome in Horses

There are several treatment options available to try to modify your horse’s behavior. After your veterinarian’s diagnosis, she will discuss treatment options with you and help you decide on the best course of action.

Gelding Stallions

Your veterinarian may recommend gelding, if your horse is a stallion. By castrating a stallion, the sexual drives that he may be experiencing should disappear within a few days and hopefully stop the self mutilating behavior. There are instances where gelding a stallion does not help and you should be aware that the behavior could become worse.


Long acting tranquilizers and antidepressants have been known to help horses suffering from ESMS. Nutritional supplements such as l-tryptophan have also been known to calm a horse and reduce the urge to self mutilate. Medications alone do not stop the behavior; they only give temporary relief by changing your horse’s focus. 

Housing Changes

Research has shown that the self mutilating behavior can be triggered by sounds, sights or smells. Your veterinarian may recommend that you change where your horse is being housed. In other words, if they are being boarded at a stable, change boarding facilities. If they are live with you, change barns, if possible, or switch stalls. 


Research has shown that a horse being housed in a tie-stall rather than a box stall has greatly reduced the self mutilating behavior. A tie-stall is a stall that is just big enough to house one horse and the horse is tied into the stall.

Underlying Cause

Some horses that suffer from ESMS have an underlying condition that is causing the behavior. Additional testing may be required to eliminate the possibility of an underlying cause of the self mutilating behavior.

Recovery of Equine Self Mutilation Syndrome in Horses

Since equine self mutilation syndrome is a mainly a behavioral disorder, traditional treatments will not be effective and treatment plans must be tailored specifically to your horse. In many cases the behavior can be changed or modified to where your horse can be redirected and not repeat the behavior. As soon as your veterinarian diagnoses your horse with ESMS, it is imperative to begin treatments and behavior modifications immediately.

In extreme cases, euthanasia may be recommended if the horse’s behavior is too severe to change or modify. Allowing a horse to continue to self mutilate would be detrimental to its health and overall well-being.

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Equine Self Mutilation Syndrome Average Cost

From 374 quotes ranging from $650 - $2,000

Average Cost


Equine Self Mutilation Syndrome Questions and Advice from Veterinary Professionals






8 Years


Moderate condition


0 found helpful


Moderate condition

Has Symptoms

Swings Head To Both Sides, Bites
Kicks Laterally Both Back Feet
Bites Chest And Lower Legs

My horse has shown some behavior that I believe is this syndrome. When he is anxious, as in his buddy is leaving him, or feeding is about to happen, or a horse on a trail ride is getting too far ahead of him, he will chomp on his chest, fidget with the bit, and today he did his lateral kick out to the side. Not at anything, just a stress releaser. He has not drawn blood, but can get worked up pretty good. He is in a huge pasture, I ride him a few times a week, and hope he can continue in endurance riding. I worry his kicks may land on another horse by accident. I've been giving him some magnesium (Mag-Restore), it's expensive, hoping to find another source. I ran out a week or so ago, and I really do think it helps with his daily fidgeting. Do you recommend a different supplement? I've had this horse 1 1/2 years, and the previous owner had him checked for ulcers, which he does not have. (Or at least not then...) I can see himself working up to acquiring them though!

Oct. 9, 2017

Tio's Owner



3320 Recommendations

Self mutilation may be either a medical issue or behavioural issue; medical issues may be caused by colic or other gastrointestinal disorders whilst behavioural issues can be more difficult to pin down. Stallions may show this behaviour and may calm down after being cut; mixing a gelding with mares; boredom is another possible cause but is difficult to pin down. If the cause is medical, treatment of the underlying cause would most likely be sufficient treatment; if the issue is behavioural, segregation and feeding forage and decreasing grain intake may help too. Regards Dr Callum Turner DVM www.merckvetmanual.com/horse-owners/behavior-of-horses/behavior-problems-in-horses http://veterinarycalendar.dvm360.com/equine-self-mutilation-syndrome-behavior-or-medical-proceedings http://research.vet.upenn.edu/HavemeyerEquineBehaviorLabHomePage/HavemeyerEquineBehaviorClinic/FrequentlyAskedBehaviorQuestions/EquineSelfMutilation/tabid/2984/Default.aspx

Oct. 9, 2017

Equine Self Mutilation Syndrome Average Cost

From 374 quotes ranging from $650 - $2,000

Average Cost