Get a Grip on Headshaking Syndrome

Last Updated on February 19, 2022 by Allison Price

This cranial-nerve disorder can be managed to improve the quality of your horse’s life.

Trigeminal-mediated head shaking, a nerve disorder that causes frequent and seemingly involuntary head tilting, could be a sign of serious nerve disorders.

Horses often shake their heads and toss about for many reasons. Horses may be trying to get rid of annoying insects or looking forward to a meal. Others may be responding to an ear infection or arthritis. Trigeminal-mediated head shaking, a nerve disorder that causes repeated and involuntary shaking, could be the cause. This condition can cause a horse to be less productive, interfere with daily routines and pose a safety risk for their handlers. It is not possible to cure all cases and each horse is unique so it is difficult to find a good management program. There is hope as research continues to identify the root cause of head shaking.

The trigeminal nerve is the largest cranial nerve and transmits sensation to the face. It also provides motor function to the muscles that are used for chewing. Trigeminal-mediated head shaking can cause horses to flicker, jerk, or shake their heads. It is not uncommon for a horse to move his head vertically up or down, but he might also move his head around or sideways. You may also notice the following signs:

Obsessively rubbing his nose against objects or forelimbs
Strike at his muzzle
Twitching lips

Snorting
An anxious expression on the face.

This is a response to facial pain that is neuropathic. Functional disturbances in the nerve can cause changes in how it processes sensory input, and lower its firing threshold. Katie Delph (DVM, MS), ACVIM is an assistant professor of equine intern medicine at Kansas State University College of Veterinary Medicine. She says that the hyperactivity of branches of the trigeminal nervous system can lead to symptoms such as discomfort and facial pain. A horse might feel burning, itching or electrical sensations on his face. It is not known what caused the nerve abnormality.

There are many reasons why and when headshaking happens. Headshaking can occur all year, but it is more common in spring and summer. It can occur when the horse is not being ridden, or it may occur all the time, intermittently or continuously. Triggers can include:

Light
exercise

Sound
Temperature
Wind

Neck position
Wearing a tack.

Trigeminal-mediated head shaking can be classified as photic or idiopathic. Photic headshakers are hypersensitive to light. Their symptoms decrease at night. Headshaking spontaneously (or idiopathically) occurs without external stimuli.

Headshaking is more common in mature geldings than in mares and stallions. The condition can occur at any age but it is most common in horses aged between 8 and 10. Headshaking does not appear to be a genetic condition. It is more common in certain breeds.

Photic headshakers are hypersensitive to light. Their symptoms decrease at night.

Confirming a Diagnose

To determine the cause of excessive head shaking, it is important to first distinguish between symptomatic behavior and trigeminal-mediated behavior.

Dr. Delph says that symptomatic cases such as headshaking can be caused by allergies, middle and inner ear infections, fungal infections in the sinuses or guttural pouches.

Dr. Delph states that affected horse owners should consult their veterinarians to rule out any potential physical issues. Headshaking should be resolved if any of these conditions are addressed.

Trigeminal-mediated head shaking is diagnosed if a physical examination reveals that the horse is healthy and continues to shake. Dr. Delph states that the next step is for the veterinarian and owner to determine the horse’s trigger. This involves “extensive observation and video recording of the horse and following the horse’s clinical signs related to weather, sunlight exposure and exercise.”

Once triggers have been identified, it is important to eliminate, reduce or minimize them from the horse’s daily routine. A horse that is triggered by sunlight, wind or other stimuli can be kept indoors in a dark stall during the day and ridden indoors at night. A Guardian mask is a face mask that protects the eyes from the sun’s ultraviolet rays. It can also help with the prevention and treatment of eye injuries and conditions. Horses respond well to a nosenet, which is a net or mesh covering that attaches at the bridle. (See sidebar above for more information about competing with a nasal net).

John Madigan, BS., DVM. MS., DACVIM is a Professor of Medicine and Epidemiology at the University of California Davis. He is a recognized expert in headshaking. The sensation they are trying to decrease is similar to when a horse presses his nose against a forelimb or wall. It’s like trying to stop a sneeze by pushing on their faces with pressure.

A horse that rubs his nose relentlessly on objects or forelimbs is a sign that he could be a headshaker.

Finding Relief

Headshaking can be relieved by certain medications, therapies and supplements. Headshaking is rarely completely cured because of the fact that every horse is unique.

Ask your vet about prescription medication to manage neuropathic pain in trigeminal mediated headshakers. Side effects of carbamazepine (an Anticonvulsant) and Cyproheptadine, an antihistamine, are common.

Your veterinarian may recommend giving melatonin all year to horses with seasonal symptoms. The body will think it’s always winter because it mimics the natural rise in melatonin when there is early darkness.

Studies are ongoing to determine the impact of nutrition on trigeminal nerve function. Dr. Madigan suggests that you consider whether any changes have occurred in the horse’s diet and climate, as well as if headshaking started around this time. He suggests adding magnesium to the horse’s diet. Although it is not a cure for the condition, it can help stabilize the trigeminal nervous system. To avoid overdose, consult your veterinarian before adding magnesium to the diet. Dr. Madigan advises that you ensure your horse is healthy and well-fed to avoid head shaking.

Top Stock is a supplement that shows improvement in horses’ performance. Top Stock, which is made of deep-sea Kelp and blended vitamins, targets overactive nerve tissue. Top Stock was tested by Dr. Madigan. There were no control variables during the trial. Owners evaluated their horses before and afterwards and reported back to Dr. Madigan. According to Dr. Madigan, the 70% success rate of the product’s trial indicates that it is likely due to the dietary influence.

PENS therapy, or percutaneous electrical nerve stimulation, is a relatively new treatment that uses a needle-sized probe. It stimulates the trigeminal nervous system and reduces hypersensitivity. It is usually well tolerated, and can help horses with neuropathic pain. It is costly and not permanent. Many horses need multiple treatments to get relief.

A headshaker can be ridden and longed depending on the severity of the situation. Performance may be compromised if the horse stops abruptly to rub his nose or flicks his head during exercise. Horses who flip their heads violently enough that they injure riders should not be ridden. You should be patient when riding a headshaker. You can’t force him to behave so don’t punish him.

Headshaking can sometimes cause serious injury to horses and affect their quality of life. A resting idiopathic headshaker can have trouble eating or display symptoms. Even severe cases of neuropathic pain may lead to self-injury. If the horse is not responding to treatment or becomes dangerously unmanageable, euthanasia may be an option.

Wearing a Guardian mask can provide relief for photic headshakers. It is designed to protect the eyes from UV rays.

Hope Found in

Headshaking is a mystery that veterinarians are trying to solve. An abnormal trigeminal nerve can cause neuropathic pain. However, current research is looking at how to treat them.

Dr. Madigan states that triggers are often overlooked. These are important but we need to understand why triggers such as exercise, light, or sound, can cause neuropathic pain. We are not trying to modify triggers but to understand why the nerve is acting in a certain way and what we can do about it.

The gated movement of certainions (channels) regulates the threshold at which the trigeminal nerve can fire. Dr. Madigan believes that the problem with the nerve is caused by abnormalities in this movement. He says, “Our research aims to find the abnormality within the channel that affects the trigeminal nervous system so we can fix it.”

A study also examined the effects of hormonal hormones on the trigeminal nervous system. It suggests that hormone dysregulation may be the reason castrated males are more prone to head shaking. The paper is currently being peer reviewed.

Trigeminal-mediated head shaking is considered a functional disorder and some horses recover quickly, so it is unlikely that the nerve is permanently damaged. The microscope actually shows that the neurons are normal. Dr. Madigan said, “That gives us hope,” and that if we understand the triggers, we can fix it.

Horses with headshakers can find relief from nose nets. However, it is important to read the rules of your discipline and speak to an official before you show your horse with one.

Nose nets in competition

Some competitions do not allow horses to use a nose net. A nose net can be beneficial for headshakers. However, you must get permission from officials before using one in competition arena. You may also be able to use the nose net for warm up, and then take it off before you compete.

The national governing body of equestrian sport, US Equestrian allows nose nets to be used in certain disciplines. The 2018 USEF Rulebook states that nose nets are only allowed under certain conditions in dressage and the dressage stage of eventing. (See below). Before using nose nets, please refer to the specific rules for your discipline or to the event official.

Rules for Events, EV115.2.g

1. An entry must be accompanied on letterhead by a letter from the horse’s veterinarian stating that the horse is suffering from headshaking syndrome.

2. The horse’s nose must be covered by a transparent material.

Dressage Rules, DR121

9. If the entry includes a signed letter from the veterinarian, a nose net can be used for warmup or competition. Each test or class sheet must include a copy of the letter. The letter must be:

a. Write clearly on veterinarian’s paper that the horse is suffering from headshaking syndrome.

b. b. On the website ( www.usef.org), you can find a list of approved dressage nose-net brands.

Before placing a nose net on a horse at a show, riders competing in International Equestrian Federation competitions (FEI) should read the rules of their discipline or talk to event officials.

Liz Holtz Messaglia has enjoyed a long and successful career with Apollo Star thanks to her careful management of the horse’s head shaking symptoms and triggers. She also won at the USEA American Eventing Championships 2011.

Success through Compromise

Liz Holtz Messaglia is an Indiana adult amateur eventer. She bought Apollo Star, a Trakehner horse, when Apollo was 12 years old. He began headshaking in the spring of 2012. Apollo has severe symptoms and Liz spent many years learning how to manage him.

Liz initially thought that the headshaking was a problem with Liz’s behavior. Apollo would throw his head violently while being led, and drag Liz around. His symptoms became so severe that she contemplated euthanasia.

His face and legs were swollen and he wouldn’t move. I had to wrap his front legs with bandages as he would rub his legs. “He started to colic because of the pain.” Liz said. Apollo’s condition improved gradually with aggressive nutraceutical and pharmaceutical treatment. Liz stopped considering euthanasia as an option.

Apollo still has headshakes, but Liz who lives with her horses recognizes and manages the symptoms. He will twitch his nose or rest his nose on the paddock fence. Liz takes him to the barn and places him in a darkened stall. This reduces light sensitivity and stops the symptoms getting worse.

She has tried numerous treatments including cyproheptadine, magnesium, allergy shots, acupuncture, miofascial-release therapy, massage, Chinese herbs, Equiwinner patches (an electrolyte-balancing product), melatonin, switching bits and bridles and more, but has yet to find a constantly effective remedy. Apollo is now 19 years old and she rides him with a Guardian or nose net. She rides Apollo in an indoor arena, and she does stretchy work to keep his relaxed. Apollo’s head shaking is not eliminated by all of this.

We stop because there are days when it is just not his day. Liz says that I have shared many [competition] entries because it is important to treat the horse right. You can’t tie your horse to a score if you have a headshaker. You must be happy that you are there and enjoy every moment.

They have competed in show jumping, dressage, and eventing in eight of the eight years Liz has been his owner. They won the Novice Amateur Championship at U.S. Eventing Association American Eventing Championships in 2011. And they also competed at U.S. Dressage Federation Region 2 Championships.