Horse Shivers and Hindlimb Muscle Disease

Shivers is a poorly understood neuromuscular condition causing involuntary hindlimb muscle spasms in horses, with significant welfare implications for affected animals.

Key Facts

Shivers is characterized by involuntary muscle trembling, hindlimb flexion, and tail elevation
It is most common in large, heavy breeds including Warmbloods, Drafts, and large Thoroughbreds
The underlying cause is not fully understood, with cerebellar degeneration implicated in some cases
Signs are triggered by backing, picking up hindlimbs, and stressful situations
There is no cure; management focuses on maintaining fitness, appropriate diet, and reducing triggers
Cases can be mild and compatible with work, or progressive and severely debilitating

Welfare Considerations

Shivers causes welfare concerns through the distress and pain associated with involuntary muscle spasms, difficulty with routine handling (especially farriery), and progressive loss of athletic function in severe cases. Horses with shivers that worsens to the point where they cannot comfortably lie down or rise are significantly welfare-compromised. The condition also creates stress during routine care such as hoof picking and shoeing, making management both time-consuming and potentially aversive for the horse. Early diagnosis, management through regular appropriate exercise, and careful monitoring of progression are essential. Research into the neurological basis of shivers is ongoing and offers hope for better treatment.

What You Can Do

Work with an equine neurologist to confirm diagnosis and rule out other muscle conditions
Maintain regular, appropriate exercise which tends to reduce symptom severity
Minimize triggers during handling - avoid backing when possible and use patient farriery approaches
Feed a diet appropriate for the horse's workload and avoid high-starch feeds where possible
Monitor for progression and adjust workload and management accordingly
Consider veterinary referral to a specialist equine neurology service for severely affected horses