A randomized double blind placebo-controlled clinical trial of Cetirizine in horses affected by seasonal headshaking

Abstract

Headshaking is a threat to the welfare of affected horses. As seasonal headshaking may be triggered by allergic conditions, this clinical trial investigated whether the second-generation antihistamine cetirizine decreased headshaking. The objective was to assess the clinical effect of cetirizine versus placebo on seasonal headshaking. The hypothesis was that it would reduce headshaking by 50 % in 50 % of the horses. Thirty client-owned horses with seasonal headshaking were selected on the basis of information from the owner and a general clinical examination. In this crossover randomised double-blind placebo-controlled clinical trial, horses were given cetirizine (0.4 mg/kg twice daily PO for 7 days) or placebo (same number of tablets twice daily PO for 7 days) in a randomised order, with a washout period of 1 week in between. A 9-minute lunge protocol was recorded on video at the start and after both treatment weeks, and the number of headshakes in this 9-minute period was scored by two assessors in a blinded manner. Data of 29 horses were analysed. The number of headshakes decreased by more than 50 % in 10 horses when they were given cetirizine and in 8 horses when they were given placebo. This difference was not significant (p = 0.73). In a mixed linear model incorporating weather conditions no significant treatment effect was found either. In conclusion: no significant effect of cetirizine on seasonal headshaking was found in the group of horses included in this study.

Comparison of the Current Situation of Equine Headshaking Syndrome in France and Switzerland Based on an Online Survey

“…It remains undisputed that symptoms of EHS can lead to dangerous situations when riding and handling affected horses [ 4 , 13 ]. A seasonal dependency with an increased occurrence of symptoms in the summer months is mentioned in the current literature [ 28 ] and can be underlined by the results of this study. The participants of this study named various causes, such as vaccinations for the occurrence of EHS.…”