Causes poorly understood - similar signs caused by sweat pea plant ingestion (lathyrism)
Distal axonopathy (esp. large diameter fibres)
Abrupt onset continuous / intermittent hyperflexion of one or both hind limbs
May also have ataxia, urinary incontinence, perineal flaccidity
Differential diagnosis : Upward fixation of patella
May get spontaneous recovery
Move pasture
Tenectomy of lateral digital extensor may help