Epidemiology of shivering (shivers) in horses.

The research article focuses on a study to understand the epidemiology of ‘shivering,’ a movement disorder in horses. The researchers performed a worldwide, web-based survey to gather data, and found that shivering usually begins before a horse reaches 7 years of age and is more prevalent in taller, male horses.

Objective of the Study

The goal of the study was to gain insights into shivering (shivers), a movement disorder in horses which is not well-defined and quite rare. The research aimed to analyze the clinical manifestations of the disorder, the specific characteristics of horses that are affected, and the management aspects related to the disorder.

Methods Employed

• A web-based survey was the primary data collection mechanism for this study. The researchers invited horse owners worldwide who had seen signs of shivering in their horses to partake in this survey.
• The standardised survey consisted of questions to gather comprehensive information and owners were also asked to provide a video of their horses.
• The authors meticulously reviewed the gathered data and videos and categorized the horses into two groups – ‘confirmed shivering’ and ‘suspected shivering.’ The confirmed group consisted of horses that showed difficulties while manually lifting the hoof, walking backward, and presented either hyperflexion or hyperextension of their hind limbs. On the other hand, the suspected group included horses that showed similar symptoms but their condition wasn’t confirmed through a video.
• The owners of the horses diagnosed with shivering were requested to share information on two other horses that did not exhibit any signs of shivering, to serve as a control group in the study.

Results of the Study

• Out of 305 surveys and 70 videos received, 27 horses were confirmed with shivering, and 67 were suspected shivering, while the remaining ones suffered from different movement disorders.
• The suspected shivering group had fewer horses from draught breeds and with exercise intolerance compared to the confirmed group.
• The beginning of confirmed shivering symptoms was often seen in horses younger than five years, and the condition progressed in 74% of cases.
• The owners reported additional clinical signs in confirmed cases that include muscle twitching in 85% of cases, muscle atrophy in 44% of cases, reduced strength in 33% of the cases, and exercise intolerance in 33% of the cases.
• A significant difference was noted in the height and sex ratio of horses. Shivering horses were significantly taller in comparison to control horses, and there was a higher occurrence in males over females.
• The study did not identify any potential factors triggering shivering and any effective treatments to manage the disorder.

Conclusion

The study concluded that shivering is a chronic and often gradually progressive movement disorder that frequently starts in horses before their seventh year of age. This disorder is more prevalent in taller, male horses.