Why does my horse only shake its head on sunny days?
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Read time: 3 minutes
Overview
If your horse only shakes its head on sunny days, the light, heat, flies or a combination of all three may be contributing. It doesn't always mean there is a serious problem, but it is worth looking for a pattern and checking for signs of irritation.
Some horses react to bright sunlight, some are bothered more by insects in warm weather, and some have a sensitivity that becomes more obvious outdoors. There can also be other causes, so it's sensible to observe carefully rather than guess.
Things To Check
1. Check whether the head shaking starts as soon as the horse goes into bright sun, or only after being out for a while.
2. Look closely for flies around the face, ears, eyes and muzzle when the behaviour happens.
3. Check for any rubbing, twitching, nasal flare, sneezing, ear flicking or tail swishing at the same time.
4. Look for redness, discharge, crusting, scabs, swelling or sores around the eyes, nose, ears and poll.
5. Notice whether it happens more in a specific field, after turnout, after exercise, or in windy conditions.
6. Check whether the horse seems more bothered by light, for example by squinting, keeping the head low or avoiding open sunny areas.
7. Review whether anything has changed recently, such as turnout times, fly pressure, grooming, bedding or tack.
Common Causes
The most common reason is fly irritation, especially when sunny weather brings more insects and more time spent outdoors. Some horses react strongly to flies around the face and ears, and head shaking can be part of that response.
Bright sunlight can also make some horses shake or toss their heads more, particularly if they seem light-sensitive or uncomfortable in glare.
Less commonly, dust, pollen, skin irritation, or an issue affecting the eyes, nose or ears can contribute. If it keeps happening, a vet may need to check whether there is an underlying cause beyond simple fly annoyance.
What To Do
Start by watching when it happens and what seems to make it worse. This can help you spot whether sun, flies or a particular environment is the main trigger.
Try to reduce exposure during the worst part of the day if you can, especially if the problem is clearly linked to bright sun. Shade, turnout timing and a calmer environment can sometimes make a noticeable difference.
Keep the face, ears and surrounding skin clean and check them regularly for irritation. If the horse is in work, make sure tack fits well and isn't adding to the problem.
If the head shaking is mild and only happens occasionally, short notes or a simple diary can help you build a clearer picture over a week or two.
When To Contact A Vet
Speak to your vet if the head shaking becomes frequent, starts happening away from sunny days, or is joined by eye discharge, marked squinting, nasal discharge, pain, or changes in the horse's breathing or behaviour. Those signs suggest it may be more than simple seasonal irritation.
Products That May Help
Sunny-day head shaking is often managed by making the horse more comfortable outdoors and reducing day-to-day irritation during fly season. This collection may be useful as part of that routine.
Horse Fly Sprays & Summer Care
Related Questions
Why does my horse shake its head more in the afternoon?
Can flies make a horse head shake without showing other signs?
When should I worry about head shaking in a horse?
Atlas is here to support owners with practical, easy-to-understand guidance. It is not a substitute for professional veterinary advice. If you're concerned about your animal's health, symptoms worsen, or something doesn't feel right, contact your vet.