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Head Shaking In Horses

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(The following is edited for anonymity and clarity.)

The post reads...

We have a new horse for my son. When we purchased him, he only tossed his head (as if a fly was bothering him) for 5 minutes or so, then he was fine. We had two weeks of non stop rain and in that time "off", he is doing this worse.

We had his teeth checked, a couple baby teeth pulled so that permanents would be straight and had his teeth floated and the problem persists. We have no problem getting the bridle on, He stands quietly when you're not asking him to do anything.

As soon as my son mounts, he starts the shaking. Sometimes the shaking is like a pulling affect, other times like a "no, I don't want to work"

During a lesson, he wouldn't stop. The next night at home he quit doing it after about 20 minutes, Today we tried draw reins and lots of serpentines and figure eights. He got better, which still makes me think because he has to concentrate on what hes being asked, he forgets temporarily to do "his thing", for about once around the ring. He's five, beautiful mover, lovely attitude, kind eye, Warmblood/ Thor. cross.

We're borrowing a KK bit that is rather fat. He really did not like a full cheek snaffle (unruly). Any more ideas? We have a Pony Club mounted tomorrow, so this should prove interesting with other horses in the ring.

There are several reasons why horses shake their heads. It can be resistance, a condition called photic head shaking, ill fitting tack, ear problems (ticks, mites, fungus), or even cervical subluxations.

In my experience with horses I find them to be very compliant as a rule and barring an obvious miscommunication or the asking for an action the horse is unable to perform, for the most part they will usually do what you ask. Since the horse stands quietly until mounted, I would tend to look elsewhere for the problem.

My guess would be photic head shaking.

The condition called photic head shaking is said to be caused by an allergy to sunlight. John E. Madigan, DVM, MS, Diplomate ACVIM, Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis who is one of the foremost researchers in this area offers the following...

"Headshaking in horses has been observed by horsemen and veterinarians for nearly 100 years. Several causes have been suggested, including middle ear disorders, ear mites, cranial nerve disorder, guttural pouch mycosis, and vasomotor rhinitis. But treatment has had little effect on this problem. In a study recently conducted at the University of California, Davis, it was discovered that headshaking was the result of a pathophysiologic mechanism similar to the photic sneeze in humans. Optic-trigeminal summation was suggested as the means by which the horse develops facial neuropathic pain in response to light stimulation.

This condition is characterized by shaking of the head side to side, up and down, acting like a bee has gone up the nose, snorting or sneezing with headshaking, and rubbing the nose on objects or on the ground while moving. The most common onset of headshaking is in spring and early summer when sunlight becomes more intense. These symptoms are usually enhanced when the horse is worked or exposed to direct sunlight. Outdoor behavior of horses which suffer from this condition suggests that the horses seek to diminish their exposure to sunlight naturally. For example, the horse will seek shady areas, or the horse may put his face right under the tail of other horses, such as following the horse in front of him on a trial ride so closely that his face is under the leader's tail.

It is thought that stress created by sunlight and exercise may trigger a response of the central nervous system that causes the headshaking response in affected horses. With these stimuli, the horse experiences a tingling sensation or inappropriate stimulation of the sensory branches of the trigeminal nerve in the muzzle area. It is also thought that alterations in blood flow could explain the sudden nasal rubbing, snorting, and flipping of the nose. The pain felt by the horse is referred to as neuropathic pain, and may be persistent or intermittent.

Also of note is that in humans it is thought that a central sensitization process following certain peripheral injuries can lead to central nervous system changes that permanently alter pain perception and thresholds, and this may hold true for equines as well.

Headshaking can manifest itself in all breeds and disciplines equally because it has a physiological basis and it can cause headaches for owners or riders. Horses which exhibit headshaking syndrome become unruly or even dangerous when they are worked, many times with the blame falling on the rider. It previously was thought that perhaps the bridle was illfitting or the rider was too busy with his or her hands. But now there is evidence that it is not the rider at all, but rather a response to the burning and tingling sensations stimulated by stress in the horse.

While nothing can be pinned down as to exactly why some horses develop headshaking and others do not, it is thought that horses which have been exposed to the EHV-1 virus are more at risk. With this theory, the herpes virus lies dormant in the horse's trigemina ganglia, then with heat and stress created by either direct sunlight or intense exercise, the virus becomes active again, this time affecting the central nervous system and producing the symptoms characterized by headshaking. More studies need to be conducted to determine if EHV-1 has a connection with headshaking, but evidence now available is pointing in that direction.

Once your horse has been diagnosed with headshaking, there are a few options available as treatments. While there is no "cure all" when it comes to treating this condition, there has been some success with cyproheptidine therapy with or without environmental protection from sunlight, or light blocking eye protectors which have been shown to provide moderate to great improvement in three-quarters of the cases which headshake. Cyproheptidine, which is an anti-seratonergic, anti-cohligenic, and anti-histamine drug, works effectively in most horses inhibiting the normal activity in the trigeminal nerve.

Because headshaking is most commonly brought on by intense sunlight and exercise, the reduction of sunlight exposure usually helps reduce the symptoms. For example, many owners have found that if they work their horses at night, the symptoms are all but gone, but if they work their horse during the day, the symptoms appear within a few minutes and worsen the longer the horse is worked. The horse should also be kept in as dark an environment as possible. So in addition to treatment with cyproheptidine therapy, you should include environmental protection that shields the horse from as much direct sunlight as possible.

Additionally, headshaking tends to be a seasonal problem in most horses. It's usually the same time each year that the horse begins to exhibit headshaking symptoms. A horse might only headshake from March to August, or in severe cases, he might headshake year round. One of the reasons headshaking shows up seasonally is that seratonin and melatonin changes occur with the changes of the seasons."

The original of this quote appears at http://www.netpets.org/horses/healthspa/head.html
Close comparison of the horse to Dr. Madigan's article should give a pretty good diagnosis of Photic Headshaking.

This is a condition that I have seen mostly in Warmbloods - Holsteiners, Trakes, Oldenburgers, etc and related crosses. I have heard it is common in Morgans as well. However, I have seen a LOT of Morgans in my time, we have a bunch of them, and I've never seen a headshaking Morgan or actually even heard of one. It is a very perplexing problem.

We have an imported high priced Holsteiner mare who began head shaking at 4 and has been unusable for nearly 20 years. We have gone the head shaking gamut, tried all kinds of remedies to no avail. She will not head shake until she is asked to work or is slightly stressed and then it starts.

The use of draw reins, serpentines, figure eights and other tricks seldom really correct anything and may cause your problem to worsen especially if it's stress related. Sepentines and figure eights are excellent limbering exercises, they really fail as vice correction methods.

Ill fitting tack should also be a fairly easy matter to resolve. One might do that by trying different headstalls and a variety of bits for the purpose of determining changes in tolerance only. I do not recommend switching from bit to bit in hopes of stumbling across one he accepts. Bit changes have pretty deep effects and playing musical bits can cause you even more problems and confusion. If changing the bit changes the habit, THEN you can decide the best way to make the change permanent.

Quite some years ago I read an article about bits, their fitting and their action by Greg Darnell in Texas. It was a piece by someone who obviously understood bits and its logic was crystal clear to me. I do not remember whether he talked about English and Western uses or not. I lost the article and only recently came across his contact info.

My next bit problem is going to get tossed into the hands of Greg Darnell of
Greg Darnell Bits
Rt.2 Box 78-A-3
Lone Oak, Texas 75453
800-809-6131

As far as the matter of ticks, mites and fungal colonies in the ears goes, that can usually be determined by a physical examination. Depending on the diagnosis, your vet will recommend a suitable treatment.

At a clinic my business and horse partner, Kellie Sharpe, and I were conducting in New York I was demonstrating how a horse who is put through the Bonder (for a free copy of the procedure, send any email to my autoresponder, Bonder@MarvWalker.com ) allows you to stick your figures up its nose, in its mouth and into its ears and do pretty much anything else you want when the horse suddenly lowered its head to remove my finger and began severely shaking his head. The owner remarked that he had a bad habit of shaking his head while being ridden and at times it made him unrideable.

Since it is almost unheard of for a horse to NOT allow me to do that after the bonder I persisted and I was able to eventually get my finger almost two inches into his ear when I felt a rock hard lump in the ear canal. I tried several times to get an idea what it was. I thought it was a very large tick, a stone or some other foreign object but the horse simply would not allow me to get near enough to it to see what it actually was at the time.

While I was at it, I began examining the horse for another cause of headshaking, cervical vertebrae subluxations. I found several cervical vertebrae that were out of alignment and recommended the horse be examined by the equine chiropractor we were fortunate to have on the grounds.

Later I was told by the chiro that the horse had the worst case of axis rotation he had ever seen. The lump I felt bulging in the horse's ear was the horse's axis. When the subluxated axis, and its related atlas were pressed by the tack, headshaking occurred.

Traditional vets tend to poo-poo chiropractic. They maintain that if the vertebrae are out of alignment enough to felt the horse would be dead. On the surface this is very true. However, what we are feeling is not the subluxation itself but the body's attempts to realign the subluxation. What we feel is the muscle and tissue response to the problem. Cervical (neck) subluxations can be the result of many things and they often cause mysterious problems. Usually, the subluxations can be adjusted and brought back to normal.

The horse's axis is located just behind the jaw curve below the horse's ear. The distance between it and the horse's jaw should be the same on each side. Ideally, you would like the jaw and the axis to be at least a good finger width apart. If they are not, or are different, you'll have a horse that will have difficulty in coming onto the vertical and in making turns.

If your horse has a tight axis to jaw ratio or an obvious difference in the two sides, you'll need to have it seen by an equine chiropractor. If you don't know where to find an equine chiro in your area Click here.

The worst headshaker I ever saw was a large Irish Draft horse that was brought to me because of an "inattention" problem. He was so bad his whole body rocked and it was dangerous to be anywhere near that huge head as it whipped around even on a leadline. I happened to see an email on one of the lists from the owner years later and sent her an email inquiring about the horse. She replied...

Marv, I never connected you with the incident. I had forgotten all about it. What a shock!!! LOL I honestly think it is an allergy. I changed his feed and took him off oats, sweet feed and put him on a pelleted feed which I can no longer get. I searched the internet ad nauseum and found a feed that sounded good. He almost completely stopped the shaking. I kept him on megabite pelleted feed until I gave him away a few months ago and he never shook again. As bad and dangerous as he was at one time it completely stopped. Children are riding him now. I read all sorts of medical reports about the condition with the addition of fly masks for the light etc. I believe with all my heart it might be oats or corn or something.

I'm sorry to say, it is the only case of headshaking I have ever heard of that had a favorable ending. Maybe the answer is in the feed.

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