Headshaking in Horses: New Therapy Gives Temporary Relief

Chronic headshaking in horses appears distressing to the horse and frustrating to the rider. Horses that display violent headshaking can’t be ridden or driven and in some cases are dangerous to handle. Various causes and treatments have been suggested, but no therapy has proved effective in all affected horses.

Irritation and oversensitivity of the trigeminal nerves are thought to be responsible for some cases of headshaking. These nerves run down both sides of the horse’s face just below the skin.

British researchers conducted a study using seven horses with headshaking related to this cause. Percutaneous electrical nerve stimulation (PENS) was performed as an experimental treatment. The horses were sedated before having a probe inserted under the facial skin and guided to the trigeminal nerve by ultrasound. The nerves on both sides were electrically stimulated for 25 minutes using alternating frequencies, a technique suggested by similar treatments on humans to relieve neuropathic pain. Six of the horses showed a positive response after one treatment, though one of these horses had increased headshaking for the first three days after the treatment. These horses were all able to return to ridden work within four to seven days.

Headshaking recurred in these horses and all horses eventually were given three or four treatments. The period between treatment and recurrence was longer after each successive treatment, with some horses remaining free of the behavior for four to six months before regressing. In two horses, headshaking behavior did not reappear after the last treatment and seemed to be cured.

For horses in this study, PENS was shown to be safe and effective in easing the signs of headshaking related to trigeminal nerve sensitivity for varying periods of time. Though this technique was not a complete cure for all horses, it is a promising advance in treating some horses that develop headshaking.