Peer-reviewed veterinary case report
Photic headshaking in the horse: 7 cases.
- Journal:
- Equine veterinary journal
- Year:
- 1995
- Authors:
- Madigan, J E et al.
- Affiliation:
- Department of Medicine and Epidemiology · United States
- Species:
- horse
Plain-English summary
This study looked at seven horses that were shaking their heads a lot, a condition known as headshaking. The researchers found no physical problems in any of the horses, but noticed that most of them started showing signs of headshaking in the spring. They tested how light affected the horses by using blindfolds, dark lenses, and observing them in complete darkness, and found that these methods helped reduce the headshaking. Additionally, five out of the seven horses showed improvement when given a medication called cyproheptadine. Overall, the treatment worked for some of the horses, but not all of them.
Abstract
Seven horses with headshaking are described. No physical abnormalities were detected in any of the cases. Six of these horses had onset of clinical signs in the spring. The role of light was assessed by application of a blindfold or dark grey lens to the eyes, covering the eyes with a face mask and observing the horse in total darkness outdoors. Cessation of headshaking was observed with blindfolding (5/5 horses), night darkness outdoors (4/4 horses) and use of grey lenses (2/3 horses). Outdoor behaviour suggested efforts to avoid light in 4/4 cases. The photic sneeze in man is suggested as a putative mechanism for equine headshaking. Five of 7 horses had improvement with cyproheptadine treatment (0.3 mg/kg bwt b.i.d.). Headshaking developed within 2 calendar weeks of the same date for 3 consecutive years in one horse. Neuropharmacological alterations associated with photoperiod mechanisms leading to optic trigeminal summation are suggested as possible reasons for spring onset of headshaking.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/8536668/