Validation of a point-of-care polymerase chain reaction assay for detection of Streptococcus equi subspecies equi in rostral nasal swabs from horses with suspected strangles.

This study aimed to validate a point-of-care polymerase chain reaction (PCR) assay for detection of Streptococcus equi subsp. equi (S. equi) in rostral nasal swabs from horses with suspected acute strangles and to compare the results against the molecular gold standard of quantitative polymerase chain reaction (qPCR). Two hundred thirty-two individual swabs of rostral nasal passages were characterized by qPCR as S. equi positive, S. equi subsp. zooepidemicus (S. zooepidemicus) positive, or S. equi and S. zooepidemicus negative. The specificity and sensitivity of the point-of-care PCR assay were 89% and 84%, respectively. The limits of detection of the qPCR assay and the point-of-care PCR analyzer were 3 and 277 eqbE target genes of S. equi, respectively. Overall agreement and short turnaround time make the point-of-care PCR assay a potential molecular diagnostic platform that will enhance the capability of equine veterinarians to timely support a diagnosis of strangles and institute proper biosecurity protocols.

Validation d'une épreuve d'amplification en chaîne par la polymérase au point de service pour la détection de Streptococcus equi sous-espèce equi dans des écouvillons nasaux rostraux de chevaux suspectés d'avoir la gourme. La présente étude visait à valider une épreuve d'amplification en chaîne par la polymérase (PCR) au point de service pour la détection de Streptococcus equi ssp. equi (S. equi) à partir d'écouvillons nasaux rostraux de chevaux suspectés être atteints de gourme aiguë et de comparer les résultats à ceux de l'épreuve étalon de la réaction d'amplification en chaîne par la polymérase quantitative (qPCR). Deux cent trente-deux écouvillons individuels des voies nasales rostrales furent caractérisés par qPCR comme étant S. equi positif, S. equi ssp. zooepidemicus (S. zooepidemicus) positif ou S. equi et S. zooepidemicus négatifs. La spécificité et la sensibilité de l'épreuve PCR au point de service étaient de 89 % et 84 %, respectivement. Les limites de détection de l'épreuve par qPCR et de l'analyseur PCR au point de service étaient de 3 et 277 copies du gène cible eqbE de S. equi, respectivement. L'accord général et le court temps de réponse font du PCR au point de service une plate-forme de diagnostic moléculaire potentielle qui augmentera les capacités des vétérinaires équins à appuyer adéquatement un diagnostic de gourme et d'instituer les protocoles de biosécurité appropriés.(Traduit par Dr Serge Messier).

Clinicopathological and pedigree investigation of a novel spinocerebellar neurological disease in juvenile Quarter Horses in North America.

BACKGROUND: In 2020, a novel neurologic disease was observed in juvenile Quarter Horses (QHs) in North America. It was unknown if this was an aberrant manifestation of another previously described neurological disorder in foals, such as equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM). HYPOTHESIS/OBJECTIVES: To describe the clinical findings, outcomes, and postmortem changes with Equine Juvenile Spinocerebellar Ataxia (EJSCA), differentiate the disease from other similar neurological disorders, and determine a mode of inheritance. ANIMALS: Twelve neurologically affected QH foals and the dams. METHODS: Genomic DNA was isolated and pedigrees were manually constructed. RESULTS: All foals (n = 12/12) had a history of acute onset of neurological deficits with no history of trauma. Neurological deficits were characterized by asymmetrical spinal ataxia, with pelvic limbs more severely affected than thoracic limbs. Clinicopathological abnormalities included high serum activity of gamma-glutamyl transferase and hyperglycemia. All foals became recumbent (median, 3 days: [0-18 days]), which necessitated humane euthanasia (n = 11/12, 92%; the remaining case was found dead). Histological evaluation at postmortem revealed dilated myelin sheaths and digestion chambers within the spinal cord, most prominently in the dorsal spinocerebellar tracts. Pedigree analysis revealed a likely autosomal recessive mode of inheritance. CONCLUSIONS AND CLINICAL IMPORTANCE: EJSCA is a uniformly fatal, rapidly progressive, likely autosomal recessive neurological disease of QHs <1 month of age in North America that is etiologically distinct from other clinically similar neurological disorders. Once the causative variant for EJSCA is validated, carriers can be identified through genetic testing to inform breeding decisions.