Common Myths Exposed

By Dr Katy Taylor,

De Montfort University

Head Shaking is not a single condition

One of the most frustrating things about head shaking is that no two horses are alike.  What causes the attacks in one horse may not in another and generalisations cannot be easily made.  It's important to recognise that head shaking is a sign of a problem with the horse and not the problem itself (although it is treated as such).  There are over 60 known causes of head shaking, including ear, eye and respiratory problems, which makes a veterinary visit all the more important.  Simply assuming your horse is an untreatable head shaker may cause them more harm. Likewise, be wary of products that claim to cure all head shakers.

It is not a behaviour or management problem

Because the head shaking is often only seen when the horse is ridden, it is commonly attributed to tack problems, bad riding, or resistance.  However, studies in the US and UK have shown that around 50% of head shakers also show symptoms at rest.  So whilst exercise always worsens the symptoms, most owners find that changes in tack or schooling have little effect. 

Researchers at De Montfort University and the University of Lincoln looked at head shakers and non-head shakers and found no important differences in their diet, use or turnout. The relative unpredictability of the condition and the symptoms seen suggest that the problem is not a largely behavioural one, like weaving or nodding may be.

Not all Head Shakers are photic Head Shakers

Head shaking has often been attributed to a reaction to sunlight, but whilst this may be so for some, especially animals in more sunny places like California, many European head shakers seem relatively unaffected by light.  Riding indoors or at dusk can still bestow benefits other than by restricting exposure to light so the best test for the photic form of this problem is to carefully cover the horse's face whilst exercising.

Head Shaking is not Horse Hay Fever

The seasonal nature of the problem (50% of head shakers only have symptoms from March to October), together with the signs of nasal irritation, has led many to believe that head shaking is a respiratory disorder similar to human hay fever.  However, the vets remain sceptical as, on the whole, drugs used for this are not very effective and rarely do they find clinical signs of an allergic reaction.  Although the horse may be responding to particles in and around the nose, an allergic reaction as such may not necessarily be occurring.

So what does cause it?

Again, remembering that there are a variety of causes, a large proportion of head shakers are thought to be suffering from some kind of pain originating within the head.  Nerve pain has long been considered, i.e. damage to the sensory nerves of the head.  This could have resulted from physical damage to the nerves or following infection of certain viruses. 

The involuntary head shake movement could be a response to the misfiring of a faulty nerve and the rubbing of the face in attempt to relieve this discomfort.  Facial neuralgia could account for the general hypersensitivity around the muzzle that many head shakers experience, particularly to rain, snow and wind.

In some cases, exercise or particles may be causing the blood vessels in the nose to swell and 'squash' the nerve, causing it to misfire.  Why some horses have a head shaking problem and not others is not yet known but since many have had the onset of their problem traced back to the beginning of their working life, the many changes that occur during this time may hold part of the answer.  Since however the problem is often not apparent until the horse is exercised the condition could have arisen earlier in its life and has lain undetected until the horse was backed.  Until we know more about what tends to cause head shaking working out how to prevent it in our foals will have to wait.