What you see. The starting point for addressing any equine health related issue is your observation.


Head Tossing or Shaking, Not while Ridden


Head tossing can range from mild and intermittent to violent and constant, and may be caused by a variety of stimuli. Anything that causes irritation to the nasal passages, skin of the face, foreign bodies or ticks in the ears, and even mouth irritation may result in this behavior. Horses commonly shake their heads when flies are bothering their face, or as a sign of excitement or anticipation.

Another poorly understood cause of mysterious head shaking is photo-activated or photic head shaking. This results in persistent head shaking, especially in bright sunlight.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours
    • If this problem seems severe and has come on suddenly.
    • If the behavior persists for longer than 30 minutes without an explanation.
    • If the results of the Whole Horse Exam (WHE) in the resting horse indicate fever (Temp >101F/38.3C) or heart rate greater than 48 BPM.
    • If the behavior seems extreme, or the horse seems to be in distress.
  • Code Yellow

    Contact Your Vet at Your Convenience for an Appointment
    • If the signs are more intermittent and mild.
    • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.

your role


What To Do

Assess the horse's general health using the Whole Horse Exam (WHE), and look for other problems or abnormalities. Assess your horse's mouth as best you can (wear gloves), look in the ears and up the nasal passages. If flies are an issue, wipe fly spray on the head and face, or place a fly mask to see if this changes the behavior. Try to determine whether the behavior is worse in bright sunlight, or associated with the transition from dark enclosures to brightly lit areas. Discuss your findings and concerns with your vet.

your vet's role

Your vet rules out other causes through careful examination and imaging, ultimately ruling in the photo-activated syndrome if there is no other explanation.
Questions Your Vet Might Ask:
  • When did you first notice this behavior develop?
  • Does this happen when you move your horse to a sunny or brightly lit space?
  • Are flies bothering the horse?
  • When did you last think your horse seemed normal?
  • What are the results of the Whole Horse Exam (WHE)?
  • How is the horse's attitude and appetite?
  • Do you notice any other problems with the horse?
  • What is the horses breed, age and sex?
  • Have you changed your horse's feed or management lately?
  • What treatments have you tried and how did they work?

Diagnoses Your Vet May Consider

The cause of the problem. These are conditions or ailments that are the cause of the observations you make.

Very Common
Less Common
more diagnoses

Author: Doug Thal DVM Dipl. ABVP