During droughts, and in the period after a drought breaks, are when we commonly see cases of stringhalt in horses. Stringhalt is when horses show a prolonged, exaggerated hindlimb flexion (a characteristic gait where the hind leg jerks sharply upwards) during forward or backward movement.
We don’t completely understand the cause of stringhalt, but it is thought to be due to a plant-derived neurotoxin, and is associated with poor quality, drought affected pastures and the presence of Hypochoeris radicata (known as Flatweed, False Dandelion or Catsear). It will commonly affect multiple animals in the same paddock at the same time. It happens more often in mature horses, particularly those that are taller. A stringhalt type gait affecting only a single hindlimb can also occur following injury to the hock region.
Most cases of stringhalt recover spontaneously once they are removed from the causative pasture. However, some horses with stringhalt have a prolonged recovery, some taking several years, and the occasional one never recovers completely. Horses with prolonged symptoms are suspected to be cases where the toxic insult has been prolonged, causing sometimes permanent changes to the nerves and muscles of the hindlimbs.
There are a number of treatments which have been attempted in horses with stringhalt, including various medications, supplements, and even surgery. However, the effectiveness of these treatments is unknown since controlled trials have never been performed, and the spontaneous recovery of the majority of cases makes any response to treatment difficult to interpret.
The most important treatment of a horse with stringhalt is to remove it from the inciting pasture immediately, and feed hay instead. The sooner this can be done, the more likely and swift recovery is likely to be.