Use of a gonadotrophin-releasing hormone vaccine in headshaking horses.

The research explores the effectiveness of using a Gonadotrophin-releasing hormone (GnRH) vaccine to treat involuntary headshaking in horses. Despite some initial reductions in specific stated hormones, the study established the vaccine’s minimal impact on the reduction of headshaking behaviors.

Objective and Methodology of the Study

• The primary goal of this research was to assess the efficacy of treating headshaking in horses using a GnRH vaccine.
• Fifteen geldings, castrated male horses, were administered two doses of the GnRH vaccine, each dose spaced four weeks apart.
• The research team gathered serum before and after the vaccine to determine the concentrations of two hormones – luteinising hormone (LH) and follicle-stimulating hormone (FSH).
• To gauge the frequency of headshaking behaviors, owners were asked to use a visual analogue scale (VAS) before vaccination and at various intervals after vaccination (two, four, eight, 12, 16, and 20 weeks).

Results of the Study

• The study found a significant decrease in the concentrations of LH and FSH hormones after the administration of the GnRH vaccine.
• However, consistent scoring did not display a substantial reduction in headshaking behaviors following vaccination.
• Of the total, roughly one-third of the horse owners reported subjective improvement in the headshaking of the geldings.
• Vaccination reactions were noted in 27% of the geldings, equating to four out of fifteen. One particular case reported severe myositis, a muscle inflammation presumed to be immune-mediated.

Interpretation of Results

• The decrease in LH and FSH hormone levels suggests that the GnRH vaccine could impact the hormonal balance in the geldings.
• Despite this hormonal change, the study found no substantial correlation between GnRH vaccination and the reduction of headshaking behavior.
• The reported subjective improvement by horse owners might be influenced by individual perception and expectation, given that consistently tracked scoring did not capture a significant decline in headshaking behavior.
• The percentage of geldings that showed vaccination reactions brings to focus the need to consider potential adverse effects when using the GnRH vaccine.