Australian stringhalt was described and differentiated from classical stringhalt in 1884. Australian stringhalt is differentiated from classical stringhalt by the severity, occurrence of outbreaks, distinct seasonal pattern and the ability of affected horses to recover spontaneously. This condition is characterised by the sudden exaggerated flexion of either one or both
hocks. This form of stringhalt most commonly occurs in the summer and autumn while horses are out on pasture. Epidemics of Australian stringhalt are usually witnessed during
drought or abnormally dry conditions.
Affected areas in the horse The long digital extensor muscle (usually in the hind limb) is the muscle that appears to be the most affected by this condition. The cause for this distal axonopathy remains unknown. Two weeks after treatment with phenytoin, significant improvement was observed in the gait abnormality of horses affected with Australian stringhalt at the trot and canter, but no significant improvement was observed at the walk or while turning.
Causes The most common plant species that have been found and identified in pastures where affected horses were located include: flatweed (
Hypochaeris radicata), sheep's sorrel (
Rumex acetosella) and couch grass (
Elymus repens). The type of nerve damage sustained in horses with Australian stringhalt suggests a mould toxin (
mycotoxin) or a fungal 'poison' found in the soils may be a cause for this condition. Mycotoxins can directly affect the long myelinated nerves in the hind limbs. ==See also==