Shivers
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Shivers is a chronic movement disorder causing involuntary spasm of the hindlimbs and tail, most evident when a horse backs up or a hind foot is lifted. In the common hyperflexion form, the limb rises, moves away from the body and trembles while the tail elevates and quivers; after seconds or longer, the foot returns to the ground. A less common form produces rigid hindlimb extension.
Large horses, including draught breeds, Warmbloods, crosses and tall Thoroughbreds, are overrepresented. Research has identified degeneration in deep cerebellar nuclei in severely affected horses, supporting a neurological basis, although the complete cause and inheritance remain uncertain. Signs commonly begin in adulthood and progress slowly.
Forward walking can appear normal early in disease, and the trot typically lacks the characteristic hyperflexion. Farriery becomes difficult because the horse cannot hold a hind foot calmly, creating risk for horse and handler. Advanced cases may show initial forward steps affected, muscle loss, difficulty rising and reduced performance. Shivers should not be confused with stringhalt, which produces brisk hyperflexion during forward walking, or with painful refusal to lift a foot.
The condition is not a behavioural refusal and punishment can increase spasm and danger. It is not contagious, and routine muscle enzyme tests may be normal. There is no proven cure. Some horses remain usable for years with modified handling, while progression can eventually make hoof care, transport or rising unsafe. Welfare assessment should focus on daily function and safe essential care rather than gait appearance alone.
Shivers produces abnormal involuntary hindlimb flexion, trembling and tail elevation, most evident when backing or lifting a foot. Forward gait can remain surprisingly normal early, and signs may be intermittent. The disorder differs from stringhalt, which causes exaggerated flexion during forward movement, and from pain-related refusal to hold up a hind foot.
Screening & Early Detection
Diagnosis is clinical. The horse is observed walking, turning, backing and having each hind foot lifted on a safe surface. Video from repeated occasions can reveal intermittent signs. The characteristic combination of limb abduction, hyperflexion and tail tremor during backward movement supports shivers, while normal forward trot helps distinguish it from stringhalt.
A full lameness, hoof, neurologic and musculoskeletal examination excludes pain, upward fixation of the patella, fibrotic myopathy, stringhalt and “standing hyperflexion”. Sedation and stressful flooring can alter performance, so examination conditions are recorded. Blood CK, imaging or electrodiagnostic tests do not provide a single definitive screen but may investigate alternatives.
Owners should document progression, falls, difficulty picking up feet and ability to rise. Prepurchase examination needs deliberate backing and foot lifting because early disease may be missed during straight forward work. There is no validated DNA test for routine breeding screening. A family history can inform caution, but cannot establish status without characteristic signs.
Both hind feet are lifted, and the horse is observed during backing after it has settled.
Treatment & Management
No medication or surgery reliably reverses shivers. Management aims to maintain fitness, reduce situations that provoke severe spasm and keep hoof care safe. Regular turnout and consistent exercise appear preferable to prolonged stall rest. Work is adapted to the individual, avoiding forced repetitive backing and disciplines requiring precise backward movement if this creates distress.
Farrier and veterinarian plan a calm environment, non-slip footing and the shortest safe period of limb elevation. The foot may be kept lower, supported on a stand or trimmed in stages. Sedation helps some horses but worsens balance or spasm in others and must be trialled professionally. Punishment and prolonged restraint are inappropriate responses to involuntary movement.
A balanced diet and normal body condition support general muscle function, but high-dose vitamin, mineral or fat supplements have not been shown to cure the cerebellar disorder. Concurrent lameness is treated because compensatory effort can reduce function. Owners review progression at least annually and sooner after falls or difficulty rising. Retirement or euthanasia becomes appropriate when essential farriery cannot be performed safely, the horse repeatedly falls, cannot rise or no longer moves comfortably enough for a good quality of life.
Breeds or species affected
Thoroughbred
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Friesian
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Dutch Warmblood
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Hanoverian
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Holsteiner
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Oldenburg
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Westphalian
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Trakehner
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Selle Français
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Belgian Warmblood
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Danish Warmblood
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Swedish Warmblood
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Swiss Warmblood
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Australian Warmblood
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Irish Sport Horse
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Württemberger
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Zangersheide
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Clydesdale
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Shire
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Percheron
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Belgian Draft
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Suffolk Punch
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American Cream Draft
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Ardennes
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Breton
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Boulonnais
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Comtois
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Dutch Draft
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North Swedish Horse
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Irish Draught
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Black Forest Horse
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