The symptoms of headshaking are snorting, sneezing, and pronounced shaking of the head characterized by a side-to-side or vertical "snatching" motion, as though the horse had an insect up its nose. Headshaking horses will often try to scratch their noses on their legs, on posts, or on the ground. Headshaking tends to occur when horses are stressed by exercise or other factors. Most important, it tends to be seasonal, triggered in the spring or early summer, and tends to subside in winter.
Scientists posit that headshaking may be triggered by strong light (photic headshaking), which stimulates the fifth cranial nerve, called the trigeminal nerve, in the horse's face and causes uncontrollable itching, pain, and/or sneeziness. (Interestingly, this phenomenon affects as many as 25% of humans as well, and is called the photic sneeze or "ACHOU syndrome.") Photic sneezing is hereditary in humans and may also be in horses. Some humans also suffer from an irritation of the trigeminal nerve called trigeminal neuralgia (TgN) that can cause facial pain and muscle paralysis. The genesis of TgN, which primarily affects women over 50, is still being investigated by neurologists; these studies may indirectly help us understand photic headshaking in horses.
Recent studies suggest, but do not prove, that headshaking may possibly be triggered by rhinopneumonitis vaccinations, which may activate the herpes virus (EHV-1, EHV-4) which lies dormant in the horse's trigeminal nerve. This process is roughly analogous to the onset of shingles in humans.
Headshaking in horses is poorly understood, and just beginning to be systematically researched. It may have multiple causes rather than a single cause. We do know that horses tend to begin to headshake at maturity. Some horses headshake all the time, while others headshake only when under saddle or in strenuous exercise. Sometimes headshaking resolves spontaneously.
the Cause of Your Horse's Headshaking
The first thing to do is to determine whether or not your horse's headshaking is behavioral - a neurotic ("stereotypic") behavior or an expression of resistance to training. Stereotypic behaviors, such as cribbing and weaving, are horses' habitualized responses to stress. Scientists suggest that the repetition of a stereotypic behavior seems to trigger the release of endorphins in the animal's brain, making the animal feel better. Some horses shake their heads (with a "rooting" motion, for example) to express irritation or resistance to work. Your trainer or a knowledgeable friend can help you sort out the difference if you're unsure.
Physically induced headshaking - headshaking in response to physical pain or discomfort - is different from behavioral headshaking and should be handled differently. If your horse is headshaking in response to pain or discomfort, punishing him is unlikely to resolve the problem. Physically induced headshaking is uncontrollable. The horse feels an uncomfortable sensation and shakes his head in response to it. It often doesn't vary whether the horse is under saddle or at large, and has been described as "looking like a massive allergy attack." A horse with severe headshaking may be unrideable, unmanageable or even dangerous, partly because headshaking can cause agitation, so use extreme care, wear a helmet and gloves, and enlist the help of others.
While you're trying to determine the cause of your horse's headshaking, keep a written diary of your horse's symptoms, the conditions under which the horse headshakes, and any observations you can make, no matter how off-the-wall they seem. Share your diary with your vet.
First, check and try the "low tech" things.
Have your horse's teeth thoroughly checked by your vet or by an equine dentist.Teeth and mouth problems can contribute to headshaking, as can a related infection of the guttural pouch.Your vet may also recommend endoscopy to determine this.
Consider consulting a certified equine chiropractor. It is possible that misalignment of the horse's spine could cause referred pain in the horse's face. One owner reports that her horse's headshaking was resolved with systematic chiropractic work.
Consider consulting a certified equine acupuncturist. One owner, Elaine P., reports that a series of acupuncture treatments relieved her horse's headshaking symptoms. You can check this article about the growth of acceptance of veterinary acupuncture.
If your horse tosses her head to one side in particular, have her ears checked by your vet. Her headshaking might be caused by a deep-seated ear infection.
A very expensive
($300-400) homeopathic headshaking remedy called Capstar is currently
being marketed at www.headshaking.com.
Homeopathic remedies work on the principle of stimulating the body's natural
immune response. However, given the fact that homeopathic remedies by definition
contain minute quantities of medicine, I question the expensiveness of this
product and am concerned that the marketers may be preying on owners who
are desperate to find a remedy for headshaking. The Capstar website
provides testimonials, but no concrete information about what "dietary supplements"
the product contains or medical evidence to prove that the product works.
(Thanks to Jennifer for discovering this link.)
Bach Flower Essences have worked for some owners. From Susan D.: "I have had some success during mild allergy months with Bach's Rescue Remedy - just a few drops before I ride seems to stop the shaking. In a bizarre coincidence, my mares allergies coincide with my own - if my ears are congested, she will shake her head. In mild allergy seasons, the RR is enough to suppress the shaking."
Current methods of allopathic
allergy testing in horses - based on human allergy tests - are expensive
and not always usefully informative. Researchers at UC Davis have recently
developed a simple blood test for IgE, the antibody that horses develop when
they suffer an allergic reaction. A blood sample drawn when the horse
is having an acute reaction will be analyzed for up to 48 different allergens
and results may be confirmed within a few days. This test may not be
available everywhere; consult your vet to find out.
If your horse is experiencing
allergies similar to human "hay fever," your vet may prescribe cyproheptadine
or a glucosteroid like prednisone that may relieve her symptoms. Cyproheptadine,
an anti-serotonergic and anticholinergic antihistamine, has proven particularly
effective with some headshakers. The price of cyproheptadine varies widely
by pharmacy, so call around before you place your prescription; in my area,
I was quoted prices from a high of $130 to a low of $23 for the same prescription.
(Thanks to Sandy for this money-saving hint.) Kalli S. has
another tip: she says " http://www.prescriptionspecialties.netmakes a suspension of
the cypro which is much more powerful than the pills, therefore allows for a
much smaller dosage. The suspension is an easy to dispense liquid in apple
flavor! MUCH BETTER."
Cyproheptadine and certain anti-seizure drugs are also reported to help photic headshaking. A recent study at the University of Liverpool by D. Knottenbelt, BVSc, suggested that the anti-convulsant drug carbamazepine, which often relieves the pain of human trigeminal neuralgia, may also be successful in treating equine headshaking. The carbemazepine was administered in concert with cyproheptadine and relieved 80-100% of the headshaking symptoms of seven out of nine horses to which it was given. However, because carbamazepine is short-acting, horse must be exercised within two hours of being dosed, making the treatment both costly and temporary. For more information, see Equus 275 (September 2000), p. 20.
Topical steroids such as xylometazoline and betamethazone, in a nebulizing (nose-spray) form, may be effective in temporarily numbing the infraorbital nerve in the horse's muzzle. Blocking the ethmoidal nerve (within the nasal cavity) has also been reported to be successful in temporarily resolving some horses' headshaking symptoms.
Some researchers theorize
that melatonin, a hormone secreted by the pituitary gland, may play a role
in photic headshaking. 12 mg melatonin per 1000 lbs, in concert with
antihistamines or alone, may help your horse. Consult with your
vet before trying this, as melatonin is a powerful supplement and can act
as a sedative.
Headshaking: When Headshaking Worsens in Bright Light
Does your horse begin to shake his head when emerging from a dark place (such as your stable) into bright light - or from the darkness of woods into the light of an open field? If so, your horse may be a photic headshaker.
Observing how your horse goes while blindfolded may give you graphic proof that your horse is a photic headshaker. Try riding your horse blindfolded or longeing him blindfolded. (I cannot overemphasize how important it is to try this test. With my horse Cody, this test revealed him to be a photic headshaker: a blackout blindfold immediately relieved his symptoms. Several owners have confirmed that this test allowed their vets to complete a diagnosis.) To be safe, you may want to ask another person to pony you, longe you, or lead you while you ride.
Headshaking in Horses. Rob Gingras. A summary of recent veterinary research on headshaking, with a bibliography of print articles.
Headshaking. An overview of information from John E. Madigan, UC Davis Veterinary School. Dr. Madigan is a veterinary neurologist who studied headshaking and other neurological disorders in horses. Dr. Madigan studied headshaking in 31 North American horses; to me, his most important theory concerns the possible connection equine herpes/rhino vaccines and headshaking. The data collection phase of this project is over, and the authors (Madigan and Dr. Stephanie Bell) published their findings in the August, 2001 issue of the Journal of the American Veterinary Medical Association, Vol 219, No. 3, 334-337.
"New Hope for Headshakers?"
Equus 275 (September 2000), 20. Discusses University of Liverpool
(UK) study of carbamazepine/cyproheptadine therapy for headshaking.
Also details test results for non-drug treatments, including tinted contact
lenses and facial masks, for headshaking.
Equine Headshaking: A Case Study by Ian S. Bidstrup, BVSc. Account/analysis of one headshaker's treatment by an equine acupuncturist and chiropractor. Dr. Bidstrup has many online articles about equine neurology.
Headshaking: A website about my own experiences with a headshaking pony is owner Sue Fairway's story about her struggles with her pony Leo, who also suffered from COPD and navicular disease.
Words of Encouragement
Don't give up. Headshaking is a very frustrating problem, but that doesn't mean it can't be solved. Many horses and owners have discovered solutions that have allowed them to keep working together. Share your findings with others so that each sufferer doesn't have to reinvent the wheel.
Do you have a solution or suggestion? Are you a veterinarian studying headshaking? Want to report a new or broken link? Do you want to be notified if there are updates to this page? E-mail me at firstname.lastname@example.org.
Lisa Jadwin & "Cody"
(Candy's Butterscotch, a
1994 American Saddlebred)
Because of his debilitating photic headshaking, which resisted all available treatments, my horse was retired to pasture at the age of 5 in December 1999.
He is enjoying his new home, where he is loved and well cared for, but my husband and I miss him terribly.
I maintain this website as a public service. I am not employed by any of the manufacturers listed above, nor do I endorse their products specifically.
This page is not intended to replace diagnosis by a qualified veterinarian or other horse professional; its author does not assume any legal responsibility. Readers should consult qualified health care providers for specific diagnoses and treatment.