Head shaking in horses is usually associated with increased exposure to sunlight. A fairly tightly woven fly mask might actually help somewhat by reducing the amount of light reaching the eye, and a drug called Cyproheptidine has been found to be fairly effective at blocking some of the endocrine and neurological pathways associated with this condition. Research by Dr. John Madigan, from the University of California-Davis, has found that head tossing in some horses, observed when the sun becomes more intense throughout spring and summer, may be very similar to "photic sneeze" in some humans. Just as only about 20 to 30 percent of humans are "photic sneezers," not all horses react to strong sunlight with head tossing, and the strength of the response varies among affected horses. There is some evidence that previous infections with EHV1 may predispose horses to the condition as well. You can find a more detailed description of this condition and treatments, written by Dr. Madigan, at this Web address: www.netpets.org/horses/healthspa/head.html.

Browse related FAQs by tag: horses, idiopathic head shaking, headtossing