What does headshaking look like?
Headshaking may look different in every horse to the untrained eye.  This is because many of the behaviors exhibited by headshakers are normal equine behaviors.  The difference between the headshaker and the normal horse is that in the headshaker, the manifestations are greater in intensity and frequency.  In other words, some horses occasionally flick their heads, headshakers repetitively and violently flick their heads.  Normal horses occasionally rub their noses, headshaking horses rub their noses a lot, and on more than just their legs (on other objects). Normal horses snort to clear their nose at the start of exercise, headshakers continue to snort during exercise; probably due to abnormal sensations in their nostrils or nasal passages.

The following are the most typical clinical signs of headshaking;

  • Shaking the head in a vertical direction (89%):  Many horses toss their heads as a part of normal equine behavior;  a headshaker will typically toss their head more violently and/or frequently.  In addition, the headshaker exhibits a particularly quick downward jerking of the head just prior to an upward flick of the head.  This particular persistent vertical shaking is not seen in the normal horse.
  • Acting like an insect is flying up the nose (88%)
  • Rubbing the muzzle on objects (75%): headshakers may have scrapes on their faces caused by this rubbing
  • Anxious expression while headshaking (61%)
  • Excessive snorting (64%): a normal horse may snort once or twice at the beginning of work, the headshaker will continue to do so many times
  • Striking at their nose

Other common clinical signs include;

  • Seeking shade in an unusual manner:  these horses may put their heads into 50 gallon drums, put their noses under the tails of other horses, or find a sliver of shade next to a building to hide their face in
  • Increase in symptoms during exercise (50%)
  • Some horses will buck & kick out while exercising when they have headshaking episodes

Other clinical signs that may be seen;

  • Staring off into the distance, sometimes followed by panicked actions. The other horses around them do not appear to see the same thing. The cause for this is not known but it may be a visual hallucination of some kind. Be careful when approaching a horse in this state.
Could my horse be a headshaker?

Each horse exhibits clinical signs of headshaking syndrome somewhat differently and unfortunately there is no one "test" that can show whether or not your horse has it.  However the diagnosis centers on the recognition of a constellation of clinical signs.  This page answers some common questions regarding headshaking syndrome, what it looks like, and what types of horses may be affected by  it.
What breeds is headshaking syndrome seen in?
Headshaking can be seen in any breed. In one study the following breeds were affected;

  • Thoroughbred (41%) (three times more likely to be affected than other breeds)
  • Quarter horses/Paints (24%)
  • Warmbloods (16%)
  • Other breeds (19%) Morgan, Arabian, Paso Fino, Appaloosa
Is my horse misbehaving?
The following information was collected in a survey of 109 owners of headshaking horses conducted at UC Davis.

Madigan, JE and Bell, SA. Owner survey of headshaking in horses. Journal of the American Veterinary Medical Association 2001; 219: 334-357.
In one survey, 93% of owners of headshakers described their horses as good, reliable horses when they were not headshaking; in fact these horses were often described as having wonderful temperaments.

It is easy to mistake the behaviors associated with headshaking syndrome for a horse that is being impatient, or ill-mannered.  The horse in the picture to the right looks as if he is refusing a command.  He is not; he is having a headshaking episode.

These horses are likely experiencing pain and distress, both physical and mental.  "Mannering" or disciplining them is not only ineffective, as it does not relieve their pain or minimize their distress, but it may compound the problem by increasing their distress.
What are headshakers used for?
No discipline is immune to headshaking

  • Pleasure riding (43%)
  • Dressage (27%)
  • Hunter Jumpers (17%)
  • Other use (6%): driving, endurance, roping

A few more bits of information about headshakers, some from studies, and some from 20 years of observation:

  • The limited amount of post mortem pathology that has been performed on headshaking horses shows that the structure of the trigeminal nerve is not damaged; therefore headshaking would appear to be caused by a biochemical dysfunction of the trigeminal nerve.   As some horses show seasonal headshaking, the trigeminal nerve also does not appear to be permanently affected and therefore there is a possibility of returning the physiology of the nerve to normal function.

  • Headshaking can develop at any age (the average age of onset is 9 years)

  • Headshaking can occur in either sex but up to 85% of affected horses are geldings

  • 64% of headshakers are affected seasonally

  • Geldings are more likely than mares to be seasonally affected

  • Seasonal headshaking tends to be significantly worse on bright sunny days and improves on rainy days, at night and indoors. Some individuals are made worse by the wind.

  • 50% of headshakers only show symptoms during exercise

  • Horses that are overweight are more likely to develop headshaking

  • Having a period of lay-up (a period when the horse is out of work) may contribute to the onset of headshaking

  • Some horses "in remission" can be stimulated out of remission by an electric shock, such as from an electric fence