Research from the University of California–Davis suggests that nose nets and fly masks may help reduce headshaking in horses.

Tooth pain, ear infection or other injury or disease can cause a horse to repeatedly toss his head or flip his nose back and forth. Usually, however, this behavior results from increased sensitivity of the trigeminal nerve, which runs along the face. In trigeminal-mediated headshaking (previously called idiopathic headshaking) the horse flips his nose, snorts and rubs his muzzle in response to raindrops, bright light, wind and other stimuli that other horses would find innocuous. Pain in the trigeminal nerve is suspected to play a role, but the exact pathway has yet to be identified.

Treatments, therefore, focus on simply relieving or decreasing the signs, and finding the right one for a horse can involve much trial and error. “While there are a plethora of anecdotal observations, there is little published evidence about what does or doesn’t work in the treatment of headshaking horses,” says Kirstie Pickles, BVMS, PhD, DipECEIM.

To learn which treatments yield the best results, Pickles and her team conducted an online survey of 130 owners of horses with headshaking. In addition to gathering demographic information and descriptions of specific headshaking behaviors, the survey asked owners if they had tried any of 11 different treatments. If they had, they were then asked if a positive response had been observed, ranging from some improvement to complete resolution. Owners were also asked to report any negative effects.

The results of the surveys showed that fly masks and nose nets, which are attached at the noseband and cover the upper lip and jaw or the entire muzzle, were considered the most effective nonmedical treatments by the horse owners. Eighty-six percent of the respondents said they had tried nose nets, with 53 percent of them reporting a positive outcome. Of those, six horses completely stopped headshaking with the nose net. Negative side effects, primarily irritation from the net rubbing the muzzle, were reported by 29 percent of the owners.

Among the 64 percent of respondents who used fly masks to control headshaking, 53 percent reported a positive outcome, with a complete cessation in three horses. Twenty-two percent of owners reported increased spooking, worsening of the headshaking or other negative side effects related to the fly mask.

Respondents also reported that fly-control measures, such as the application of fly spray, reduced headshaking—21 percent of owners reported a positive result.

Nine percent of owners reported using a combination of the hormone melatonin and magnesium, with a positive outcome in 55 percent of those cases, but no horses had complete resolution.

Adverse effects, seen in 36 percent of the horses, included weight gain, lethargy and non-shedding of the hair coat. Pickles says that owners can best utilize this information in a discussion with their veterinarian about the best approach for their particular horse. “Usually physical methods, such as nose nets, are tried first as they are pretty effective, cheap, and have relatively few deleterious side effects.”

Reference: “Owner-reported response to treatment of 130 headshaking horses,” AAEP 60th Annual Convention Proceedings, December 2014

This article first appeared in EQUUS issue #452

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