Veterinary advice should be sought before applying any treatment or vaccine.


Idiopathic Stringhalt, Hahnentritt

Stringhalt is a locomotor-induced movement disorder of horses involving spasms of one or both hindlimbs during movement, which appears as abnormal, exaggerated flexion of the hocks. The severity ranges from mild hyperflexion to violent movements involving the foot touching the horse's belly prior to landing on the ground. Stringhalt is most noticeable when horses are asked to back up or when turned. Symptoms may also worsen during the colder months of the year.
Image of a typical horse with stringhalt
Stringhalt is generally classified into two sub-groups, which include plant associated stringhalt (also known as Australian stringhalt) and sporadic or idiopathic stringhalt.

Australian stringhalt: Australian stringhalt, also known as plant-associated stringhalt, is caused by eating certain toxic plants in horse pastures. The most common plant known to cause stringhalt in horses is flatweed (Hypochoeris radicata), but there have also been less common cases involving sweat pea (Lathyrus odoratus) and vetch (Vicia genus).


Sudden hyperflexion of one or both hindlimbs
Muscle atrophy
Gait abnormality
Appears like the horse is always stepping over something
Appears like a bunny hop


  • History
  • Clinical signs
  • Physical exam
  • Electromyography



Botox injectionsUsed to decrease the hypermetric response.
Lateral digital extensor myotenectomyA surgical procedure that results in removal of a portion of one of the tendons crossing the hock. It has been associated with varying success.
Phenytoin and thiamineLarge doses help to reduce aberrant peripheral nerve activity and excessive muscle contraction.
Controlled exercise and turnout



Guarded to poor for performance but excellent for life.

Scientific Research

General Overviews

Risk Factors

  • Letting horses graze in pastures that contain flatweed, sweat pea, or vetch plants.