Headshaking - Photic Headshaking - Photo Sensitivity
This information is designed to help those of you who have (or think you may have) a "headshaker". Headshaking is a distressing condition for both horse and rider. Although being increasingly studied, very little is known about the cause of abnormal headshaking in horses. As a result, owners are desperate for information and that which is available is often confusing or specific to a researcher's particular area of expertise. What follows is a comprehensive guide to headshaking syndrome, including what behaviors your horse may have, why they may be a headshaker and how you can help them.
What Is Headshaking?
In the literature, headshaking is described as the sudden, intermittent and apparently involuntary tossing of the head. It can occur to such an extent that both horse and rider are thrown off balance or the unfortunate rider is knocked in the face. It derives from the horse's normal and natural impulsion to shake the head when bothered by flies in the field or when feeling frustrated (at the start of a race).
However, a horse is called an abnormal headshaker when this shaking occurs under saddle and for no apparent reason. The severity of symptoms can vary widely between individuals, so widely that the distinction becomes unclear between those that are classic headshakers and those that are "nodders" or "head bobbers" (those that shake their heads more out of boredom or frustration rather than for the reasons that follow).
At the other end of the extreme, some headshakers are so dangerous and distressed that they have to be put down. Worryingly, many headshakers are sold on to unsuspecting owners, especially in the winter months when headshaking is often less apparent.
Clinical Visible Signs
Main sign - sudden and apparently involuntary, vertical tossing of the head when ridden.
Very often occurs only after 10 minutes into exercise, i.e. when the horse is warmed up and frequently at the trot, though headshaking can occur at any pace.
Some horses shake all year round but the majority show a distinct seasonal pattern, the headshaking beginning in the spring (April onwards in the UK) worsening over the summer and easing into autumn. These horses appear symptom free over the winter with only the occasional bout (often on bright sunny days).
Horizontal or rotary headshaking.
Headshaking at rest (i.e. when in the field, in the stable, or when being led).
Flipping of the upper lip.
Acting as though a bee has entered the nostrils.
Headshaking more when excited or stressed.
Snorting and or sneezing frequently.
Attempts to rub their nose on objects whilst moving, e.g. your leg, the ground, their foreleg, stationary objects.
Striking out with the foreleg, often towards the muzzle or nostrils.
The horses may also exhibit some of the following
Attempts to avoid sunlight by placing their head under the trail leaders tail, in water (including water trough) or dense plant undergrowth.
Visible inflammation in the eyes, runny or watery nose and or eyes.
Swellings may appear on the face
Sweat patches appear on the body
Stumbling, even falling
Breathing may be labored or sound odd
They may approach seeming to be out of sorts, peculiar, at times either "spaced out" or staring into space. Horse may even seem panic filled and out of control. Could also appear to be or dopey and lethargic.
They may even 'clamp' their nostrils
After an attack your horse may continue to:
Sneeze or snort
Rub its nose on objects, e.g. you!, stable doors, walls, or posts.
Display a runny nose or watery eyes
Appear uncomfortable, distressed or just dopey. References (Lane & Mair 1987)
There is not one, sole cause of headshaking. It is a 'presenting sign' of disease, and excessive headshaking is merely an expression that something is wrong and/or irritating the horse. Headshaking has been associated with nearly 60 diseases and conditions, including, EPM, ear mites, eye problems, guttural pouch mycosis and vasomotor rhinitis (Cook 1980b, Lane & Mair 1987). Usually these diseases will show other symptoms along with the headshaking that can be used to diagnose the disease.
However, many of you will have checked your horse out with the vet and they may have found no apparent signs of disease. Their behavior may also fit into a common pattern - see clinical signs. In this case, your horse may be what is commonly referred to as an idiopathic headshaker (Lane & Mair 1987), which is treated very much like a disease in itself, there being no other apparent signs of disease only the headshaking.
Immediate causes or triggers for idiopathic headshaking may be riding near oil seed rape fields in bloom or being in bright sunlight and are what owners often manage to identify themselves. Underlying causes, the real reason the horse is headshaking, are harder to establish for example, allergic rhinitis.
There is also a difference between the cause; for example, allergic rhinitis and potential risk factor such as being over exposed to an allergen at an earlier stage. An identification of potential risk factors may help reduce the incidence of each different kind of headshaking. At the moment little is known about how the range of symptoms that the horse may suffer from can differ, depending on the cause. You may see aspects of your horse's behavior in all of the below descriptions.
My research focuses on ways in which we can clearly define potentially distinct types of idiopathic headshaker. This is necessary before we can hope to find meaningful treatments and identify risk factors. It is recommended that you get your veterinarian to thoroughly look over your horse. This is especially important if its behavior is severe or different from what has so far been described. It may also be worth checking that its back is not painful and your tack is not hurting either.
I've checked him out and found nothing - why?
The mechanisms causing the headshaking maybe something we can't easily see, e.g. allergic reactions or nerve sensitivity.
Riding near hedgerows, trees, airable crops especially oilseed rape
(during the pollen season, or possibly when being sprayed).
Midges and small flies annoying the horse.
Being touched in a sensitive area (muzzle, poll or face), even snowflakes or light rain may set the horse off.
Stress - at shows, being put with strange horses.
Loud or sharp noises.
Underlying Causes - Allergic Rhinitis
Some horses may be suffering from an allergy similar to hay fever. Things that may trigger them off include riding them through arable crops, trees, etc. They may show an obvious seasonal pattern but together with cross pollination factors and a general worsening/hypersensitivity of the condition, they may also do it at other times. They may sneeze or snort, their nose may run and eyes look sore. They may seem worse in bright sunshine as humans often do when suffering from hay fever. References Lane & Mair (1987,1993).
Allergens such as pollen, oilseed rape volatiles, dust, etc get into the horse's nose. An allergic reaction occurs in the mucus membranes that line the inside of its nasal passages. Inflammation and creation of mucus stimulates irritant nerve receptors in the nasal passages, which irritate the horse, and so it throws its head up.
What can I do?
Look for common factors and coincidences occurring at the time your horse has a headshaking attack in order to work out what may be the offending allergen.
Avoidance tactics, i.e. avoid these!
Consult your vet. There may be some drugs that will help which only vets are qualified to administer.
Try using a nose net, available from equilibrium, your local saddler or make your own out of the foot of a pair of tights tied to the noseband. It may act to filter out pollens, but is more likely to act as a counter stimulant.
Allergy neutralization - React Clinic, or consult an alternative vet.
Underlying Causes - Photic Headshakers
These types of headshakers may be easier to spot and this certainly seems to a major cause of headshaking in the US. These horses are usually obviously worse in sunlight and may actively hide their heads in the shade or in a companion's tail. Their eyes may appear sore and water as well. Try lunging your horse with a blindfold on or indoors or at night to see if this is the case. If his headshaking is much improved then he maybe reacting to the sunshine.
References John Madigan et al (1995).
Your horse may be suffering from a phenomenon similar to the photic sneeze syndrome in humans. Stimulation of the optic nerves (behind the eye) by light can also cause stimulation in other nerves within the head. Reactions that follow include constriction of the pupils and in some cases lacrimation (watery eyes) and nasal membrane reddening. The irritation of mucus and alterations in blood flow within the nasal passages may cause the horse to shake its head, snort and sneeze.
There is an additional theory as well: These horses may have had some previous damage to the muzzle area and their threshold to pain caused by this 'referred stimulation' has been lowered, or they have been in contact with the EHV1 flu-virus (or possibly the vaccine) when younger. Sunlight, stress or exercise may make this virus more active and it causes increased stimulation of the trigeminal nerve, which conducts sensation from the muzzle to the brain. The horse starts headshaking as a result.
What can I do?
Consult your vet. Possible drugs which only they can advise you about, for example, Cyproheptadine or Periactin. Melatonin may help as hormonal imbalances may make the horse more sensitive to sunshine in the summer - speak to your vet
Try using a face net to shield your horses eyes and face from the sunlight
More extreme cases will need total protection from the sun (but with vision unimpaired)
Avoidance tactics - Ride him indoors if you can, if not at night (but use your common sense!), sometimes dawn or dusk is still okay.
Provide shelter from the sun for his own comfort when not being ridden
Underlying causes - Bit Intolerance/Pain
Your horse may not show any clear seasonal patterns to his headshaking, or his headshaking may only occur when being ridden. If he ceases to shake as much when not under saddle or with a bit in his mouth then the cause of his headshaking may be bit pressure causing nerve pain. A good test for this is to lunge your horse in a head collar only. However, your horse may continue to experience 'ghost' feelings of pain for sometime after the bit is removed or the headshaking may have turned into a habit and this test may need to be repeated several times.
Considering what we put our horses through, it is surprising how many allow us to tack them up and ride them in all sorts of strange ways without problem or complaint. However, Professor Cook at Tufts University believes that by placing a bit in the horse's mouth we are putting abnormal constraints on the horse. Not only does putting something in its mouth and asking it to exercise confuse the horse (it might think it should be eating!), but also constant pressure by the bit may be causing pain in the mandibular branch of the trigeminal nerve.
Your horse may be headshaking due to intolerance of this confusing lump of metal in its mouth or because the bit is directly causing neuralgia (nerve pain). Add to this the possibility that the bit increases the likelihood of poll flexion (bending of the neck from the poll) which makes breathing harder and it is not so surprising that we occasionally get problems like headshaking. Headshakers suffering because of the bit may still show seasonal patterns as they may be worked more in the summer or the increased heat may exacerbate the problem. References (Cook 1992 & 1999).
What can I do?
Professor Cook advocates the use of a bitless bridle and claims excellent results for all headshakers. Whether the bit is the direct cause or not, it certainly makes sense to consider using this more humane bridle anyway. Maybe one day all horses will be in one and bits will be a thing of the past.
Underlying Causes - Hypersensitivity
Your horse may just have a sensitive muzzle and so anything, e.g. rain, snow, flies or sweat from exercise touching him in this area may set him off headshaking.
The nerves in your horse's muzzle may be inherently hypersensitive or may have been damaged in the past causing them to be more sensitive than they were. Small objects touching the muzzle may stimulate the sensory nerves causing irritation, which the horse reacts to by throwing its head up. Stress may also lower the horse's threshold to pain and irritation.
What can I do?
You may find your horse benefits from a nose net, not for its filtering abilities but because it acts as a counter stimulant. Some horses are desensitized by using this and will not shake even if the initial irritant appears.
A fly fringe or Nose Shaker, similar to what you put on the head collar may work just as well if placed lower down, hanging from the nose band.
Underlying Causes - Behavioral problems
As explained before, there is some confusion as to what is and what isn't a headshaker, especially among owners who haven't yet consulted their vet because the symptoms aren't that bad.
Just because your horse so far doesn't show any seasonal patterns and you haven't noticed any other patterns doesn't mean he isn't an idiopathic headshaker and is a 'bad' horse. He may have been a seasonal headshaker in the past and his symptoms have worsened so that he shakes intermittently all year round. His headshaking may have also turned into somewhat of a habit as well. You may find that he shakes his head more when annoyed, frustrated, stressed or conversely, bored. His shaking may be reduced by making him concentrate, i.e. jumping or interesting flat work, but this is often also the case with allergic headshakers (if you think about it you can often stop sneezing if your mind is taken off it).
However, if his head movements are more rhythmical, occur towards the end of a ride, when you feel he might be bored or occur at rest in the stable, and he does not show any signs of irritation/inflammation, then he may have a purely behavioral problem.
What can I do?
If you feel the only reason he shakes is frustration, stress or in annoyance, then consider the situations in which he shakes and see if you and another experienced horse rider may be able to find solutions to these situations.
Do not force him into behaving by using brute force/heavy discipline, nor do we suggest you use a stronger bit or reins to control him. He is headshaking for a reason and not just to make life difficult for you!
He may be happier in a bitless bridle.
Don't take him to places where he gets stressed or place him in stressful situations.
If its boredom, make his life or riding lessons more interesting!
Consider re-schooling him, using non-physical, non-confrontational techniques.
Search for animal communicators and trainers near you, or ask your vet or riding school to recommend someone.
The many other causes...
There are a lot of diseases and conditions that may cause a horse to headshake. These include:
Respiratory problems and infections resulting in blocked airways, e.g. guttural pouch mycosis
Central neurological problems and diseases e.g. EPM
Hormonal problems, e.g. Cushing's Syndrome
Ear mite infestations and or Middle ear problems
Usually these are rarely the sole cause of the headshaking, as upon correction of the problem the headshaking may re-occur. But this doesn't mean that the problem itself should be ignored! You should consult your vet to rule these out initially.
Techniques that owners have reported having helped their horse
Nose nets - either manufactured ones (see your saddler) or home made ones with a pair of tights or pantyhose. Our work showed that these at least partially helped over 60% of horses that had tried it. They may not filter out allergens as previously thought, but act as a counter stimulant, a kind of soothing rub, which makes the horse ignore any other itches. You will probably find that your horse either loves or hates it. If he does take to it you may find that you can now ride him with it on as you did before.
Fly fringes over the nose - may work like the nose net but are more aesthetically pleasing - try taking the fly fringe and putting on the nose band so it hangs over the horse's nostrils.
Homeopathy - nearly 40% of owners who had tried this felt it at least partially helped the horse. Ask your vet to recommend a homeopathic vet to you. Or see Capstar or Hilton Herbs. You must persist with your homeopathy treatment, it is not necessarily a quick fix (it may take months).
Face Masks - with 95% Sunshades from Guardian Mask Particularly worth a try if you think your horse suffers from the UV rays of the sun.
Ride indoors (to avoid sunlight, wind and the majority of allergens).
Adjust or change your tack, look for 'kinder' alternatives rather than harsher ones, consider the bitless bridle.
Move your horse to a different field/livery, esp. worth it if you live right next to a rape field or other crops!
Try riding in a different area if you can't move, e.g. on the beach, on roads, grassed areas.
Ride early morning/late evening.
Try putting an ear net over his ear, especially if he seems bothered by flies in this area.
Herbal supplements, for breathing and allergies (Hackaway or Freeway) or temperament (Response or Temperament ) from Hilton Herbs, for allergies try Echinacea from Equine Health & Herbal.
Change the level or type of work he does, he may prefer to work less or more.
Olive oil & vinegar on the nose.
Aromatherapy (keeps flies away too!) - 20ml of sweet almond oil mixed with 5 drops each of tea tree, lavender & Geranium oil, shaken and applied to horse's forelock, muzzle, jaw line and base of ears (Mrs. S. Clegg). Try also citronella, Vicks or eucalyptus oil as a fly repellent. Be careful with these oils as some horses have very sensitive skin and may react adversely. Consult your vet first!
Try putting a high sunblock on his nose.
Try cutting sugars out of his diet - check with your vet first.
Some people have tried magnesium, phosphorus or Vitamin C supplements. Consult your vet first!
Soaking hay to reduce the possibility of hay allergies.
Friars balsam to clear up breathing problems.
Electrotherapy on the back.
Acupuncture. Always remember to seek the advice of your Veterinarian before treatment.
N:B - All of the above information and advice comes directly from Guardian Horse