Headshaking can be very frustrating. Although it’s fairly common, it can be difficult to get to the bottom of and treat effectively. It’s actually a clinical sign and, as such, can have a number of underlying causes. 

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When to worry about headshaking?

It’s perfectly normal for all horses to shake their heads at some time or another. Thankfully, in general it’s just a defence mechanism aimed at agitating and dislodge any pesky flies. So, if you see your horse shaking his head when there are flies about, they are probably the culprit.

You’ll probably see a lot of tail swishing and maybe stamping as well. In the case of bothersome flies, it often subsides as the horse gets moving when working. But sometimes these bugs can be pretty persistent and distract him even when being ridden. In the summertime, it’s always advisable to use plenty of equine-appropriate fly repellent. You may also want to use fly rugs and masks in the fields, and nose net as well as ear covers for when the horse is being ridden, to try and keep any nuisance to a minimum.

Headshaking that is persistent, worsening, doesn’t respond to bug control, is present year-round, or only occurs when ridden, is likely to be caused by something other than simple annoyance from flies. This warrants some investigation. So if you see such signs, then it’s best to have your horse booked in to be seen by your local vets to investigate what’s going on.   

What are the possible causes of headshaking?

In our equine friends, headshaking can be a sign of a number of different disease processes. 

Dental disease is a key one

There are many reasons for oral or dental discomfort. Headshaking is often a way of the horse expressing that something inside his mouth is bothering him. This highlights the importance of regular dental check-ups for horses, and an oral exam will probably be one of the first things your vet will suggest.

Sinus problems can be another culprit, and sometimes because of a tooth root problem such as infection or abscessation. Depending on the results of his dental examination, your horse might need some X-rays taken to get a better look at the sinuses. It could even be that your horse’s headshaking reflects the discomfort it feels having inhaled some foreign material up into the nasal passages.

Next up, guttural pouch disease. 

Guttural pouch mycosis involves fungal infection of this hidden-away structure. These horses might have other signs like discharge or bleeding from the nose. A camera (endoscope) is used to examine it for any sign of infection and take samples if needed. 

It might be that headshaking is the horse’s way of defying its rider. Or perhaps an escape route for the weaker horse, trying to evade doing work that it finds physically challenging. Equally, musculoskeletal problems of the head, neck and back may also manifest through headshaking. This means that further x-rays or other imaging modalities might be needed in the veterinary work-up. 

“Trigeminal Headshaking”

There are some horses where investigations come up with no obvious reason behind their headshaking. We are becoming more aware of idiopathic headshaking or idiopathic trigeminal-mediated headshaking. This is headshaking of an unknown cause, suspected to result from the sensation of pain in the face.

In idiopathic headshaking, it seems like the nerve supplying sensation to the face isn’t working properly. As well as headshaking, these horses might rub at their faces and snort and it’s often worse when the horse is being ridden. The condition is suspected in horses where another underlying cause cannot be found, and particularly where signs have shown to improve after infiltration of the nerve with local anaesthesia, blocking the pain (but not all horses respond).

What can be done for a headshaking horse?

The treatment of headshaking really relies on its underlying cause, this is why a thorough investigation is needed to try and get to the root of it. In many cases, identifiable conditions (such as dental disease or a nasal foreign body) are behind the headshaking, and appropriate treatment resolves the problem.

In idiopathic headshaking, treatment can be difficult. Although around a quarter of affected horses will improve just using a nose-net, there is no known effective treatment that works in all cases and further studies are needed to deepen our knowledge of the condition. Nerve stimulation is often recommended as a second-line treatment, however, severely affected horses who don’t respond to attempted treatment may, sadly, eventually need to be euthanised.  

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