Stringhalt is a sudden flexion of one or both hind legs in horses and donkeys, most easily seen while the animal is walking or trotting. It is most evident when backing up slowly, turning on the affected leg, or suddenly frightened. It can involve one or both hind legs. It is a spasmodic contraction of the lateral extensor tendons of the hind legs. thumb|right|An example of bilateral stringhalt in a horse: the hocks are spasmodically and rapidly flexed with the feet held high before quick placement back on the ground. The condition is more evident during turning and backing.
Stringhalt is a sudden flexion of one or both hind legs in horses and donkeys, most easily seen while the animal is walking or trotting. It is most evident when backing up slowly, turning on the affected leg, or suddenly frightened. It can involve one or both hind legs. It is a spasmodic contraction of the lateral extensor tendons of the hind legs. thumb|right|An example of bilateral stringhalt in a horse: the hocks are spasmodically and rapidly flexed with the feet held high before quick placement back on the ground. The condition is more evident during turning and backing.
There are four forms of stringhalt: Australian stringhalt: a flatweed (Hypochaeris radicata) is the suspected cause Pseudostringhalt: the apparent result of a painful condition in the affected leg Unilateral stringhalt: cause unknown, but often relieved by section of the lateral extensor tendon Bilateral stringhalt: in two out of two affected horses necropsied, abnormal thalamus
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