The Problem of Headshaking

This is a condition called photic headshaking and a horse that spends most of their turnout time with their nose buried in a pasture mate’s tail is another showing signs of the condition.

This condition typically appears seasonally as the days get longer which means this unusual behavior is suspected to be caused by allergies. While allergies may be a factor in some cases the bright sunlight is actually considered to be the prime culprit after other causes have been ruled out.

The irritated nerve may become painful in some cases which results in the headshaking. This nerve exit’s the skull about four inches behind the nostril which, when irritated, can cause the horse to shake their head and rub their nose on the ground in order to get relief. Horses may learn that they can avoid irritation by avoiding sunlight whether this be to standing in the darkest corner of the stall or burying their head in a pasture mate’s tale.

This condition seems to be triggered by exercise and almost always aggravates the condition. Other causes for headshaking should be ruled out first if the horse shows no clinical signs except during exercise since it could be caused by tooth problems or resistance to training.

Headshaking may be caused by any type of bits. To decide if this is the solution for a horse with headshaking that only shows signs during exercise there is a simple test that you can use.

On a sunny day, lunge the horse in a halter and allow sufficient time for the nerve to become stimulated. A bitless bridle likely won’t solve the problem if headshaking occurs. If headshaking is eliminated or greatly reduced by using a blindfold or lunging after dark then the problem is likely caused by direct sunlight.

With some success, the drug cyproheptadine has been used to treat photic headshaking whether used alone or in conjunction with melatonin. Cyproheptadine affects the transmission of nerve impulses even though it is an antihistamine and may also help to block excessive stimulation to the branches of the trigeminal nerve.

You may be able to prevent the onset of sensitivity to bright sunlight that is associated with spring, summer and fall by supplementing the body’s natural melatonin levels to where they equal the levels found in the winter months.

A surgical procedure is available if therapy with cyproheptadine and melatonin is not successful and can be used to treat persistent cases of photic headshaking. A definitive diagnosis should be made by a veterinarian before surgery is performed. A diagnosis can be obtained by blocking the trigeminal nerve with a local anesthetic.

A trigeminal neurectomy may be effective if there is no evidence of headshaking while the nerve is blocked. Before the surgery is planned you should have the block done at least a week in advance to allow the swelling from the block to subside. After a properly performed surgery, the facial drooping that is present during the nerve block will not occur again.

The procedure is uncommon so it is good to seek an experienced surgeon even though the procedure is uncomplicated. About three weeks after surgery the horse may be put back to work. Even surgery may not offer a permanent solution since there is the possibility that the nerve will grow back.