Pasture‐associated stringhalt: Contemporary appraisal of an enigmatic syndrome

Abstract

Summary Although described clinically for several centuries, stringhalt remains an intriguing and enigmatic condition. In pasture‐associated stringhalt (PSH), the clinical sign of exaggerated, prolonged hindlimb flexion is associated with a peripheral neuropathy affecting the larger myelinated axons that is thought to be the result of exposure to a plant‐derived neurotoxin. It is likely that multiple host and environmental risk factors interact to produce PSH and the precise aetiology has not yet been elucidated. Drought‐affected, poor‐quality pasture and the presence of Hypochoeris radicata (commonly referred to as Catsear, Flatweed and False Dandelion) are recognised risk factors. Affected horses are typically mature and taller animals are considered more susceptible. Most horses with PSH recover spontaneously if removed from the presumptive source of toxin; however, recovery can be prolonged, taking several years for some horses, and might be incomplete in occasional cases. A wide range of therapies have been attempted in horses with PSH including phenytoin, thiamine, taurine, infiltration of digital extensors with botulinum toxin and lateral digital extensor myotenectomy procedure. The efficacy of these treatments is uncertain since controlled trials have not been performed and the spontaneous recovery of most horses makes any response to treatment difficult to interpret.

Commercial genetic testing for type 2 polysaccharide storage myopathy and myofibrillar myopathy does not correspond to a histopathological diagnosis

“…To supplement the number of control‐WB, additional WB were selected from samples submitted by referring veterinarians to the Neuromuscular Diagnostic Laboratory, from across the United States with the criteria that there were no evident histopathological findings in haematoxylin and eosin, modified Gomori Trichrome, nicotinamide adenine dinucleotide tetrazolium reductase, oil red O, PAS, amylase‐PAS and desmin stains. Preference was given to samples from horses with a history consistent with shivers or stringhalt because these are not muscle diseases 22,23 . There were 11 control‐WB that had no clinical signs of muscle disease, 16 with a primary complaint of shivers/stringhalt, 10 with a hindlimb gait abnormality (ataxia, weakness and lameness), seven with atrophy/fasciculations, five with poor performance, three with ER and two with muscle soreness.…”

“…Preference was given to samples from horses with a history consistent with shivers or stringhalt because these are not muscle diseases. 22,23 There were 11 control-WB that had no clinical signs of muscle disease, 16 with a primary complaint of shivers/stringhalt, 10 with a hindlimb gait abnormality (ataxia, weakness and lameness), seven with atrophy/fasciculations, five with poor performance, three with ER and two with muscle soreness. TA B L E 1 The gene, Ensembl transcript ID used for annotation, chromosomal location, cDNA sequence variation and amino acid substitution for the P2, P3a, P3b and P4 variants with reference to EquCab3…”

Management of idiopathic stringhalt in a 14-year-old thoroughbred gelding in Nigeria: A Case Report

“…The most common signs of the condition are involuntary, exaggerated upward movement of the hind limb, kicking upwards towards the belly, hopping or jerking, incoordination, dragging hind hooves, muscle atrophy of the lower hind limb, and the inability to stand up without assistance (El-Hage et al, 2019;Valberg and Baird, 2022).…”

“…The diagnosis of stringhalt relies on observing clinical signs and ruling out other neurological and orthopedic abnormalities. This process may involve techniques such as electromyography (EMG), nerve conduction velocity (NCV), and diagnostic imaging (El -Hage et al, 2019). When intoxication is suspected, relocating the horse to a different paddock, providing an alternative source of feed and water, and identifying and collecting samples of the suspected toxic plants from the horse's environment for analysis may be sufficient, and many cases seem to recover spontaneously.…”

Tratamento cirúrgico para harpejamento idiopático em equino: Relato de caso

“…A segunda forma do harpejamento é a bilateral, conhecida como harpejamento australiano ou adquirido, que ocorre de forma sazonal, em surtos ou casos isolados (MARTINEZ, 2007). Esta forma tem sido relatada na Austrália, Nova Zelândia, América do Norte, Brasil, Itália, Chile e Japão (PELOSO apud AUER; STICK, 2012), podendo ser resultado da exposição a neurotoxinas e subsequente neuropatia periférica, ou a neurotoxinas derivadas de plantas (EL-HAGE et al, 2017) do tipo Taraxacum officinale, Malva parviflora, Hypochaeris radicata, Rumex acetosella, Elymus repens, que predominam nas pastagens em épocas de seca (BAXTER, 2011;BROCKMAN, 2016;DEL PIERO;ROBERTSON, 2015;PELOSO, 2012;SULLINS, 2011). Acredita-se que possa ocorrer uma neuropatia periférica (axonopatia) e atrofia muscular neurogênica do extensor digital longo e lateral, músculo gastrocnêmio e cricoaritenóideo dorsal (BAXTER, 2011;PELOSO, 2012).…”