Ganglion Cytology: A Novel Rapid Method for the Diagnosis of Equine Dysautonomia.

Authors: Piccinelli Chiara, Jago Rachel, Milne Elspeth

Journal: Veterinary pathology

DOI: 10.1177/0300985818806051 PubMed: 30286693Log in to save

Summary

Equine dysautonomia (grass sickness) causes irreversible degeneration of autonomic nerve cells and carries a poor prognosis, making rapid antemortem or early postmortem diagnosis critical during disease outbreaks; however, current diagnostic protocols rely on time-consuming histological examination of tissue samples. Piccinelli and colleagues evaluated whether cytological smears obtained by scraping the cranial cervical ganglion could provide faster results with diagnostic accuracy comparable to standard histology, using three different staining techniques (May-Grünwald Giemsa, haematoxylin and eosin, and cresyl fast violet) across 16 confirmed dysautonomia cases and 20 control horses. When all three stains were assessed together, the technique achieved 100% sensitivity and specificity; May-Grünwald Giemsa alone proved most reliable, though occasional samples (3.7%) yielded insufficient cellular material for confident interpretation. For equine practitioners, this work suggests that rapid ganglion cytology could facilitate faster diagnosis during suspected dysautonomia cases, potentially allowing swifter farm management decisions and disease outbreak control, though the technique requires careful technique to ensure adequate sample cellularity and interpretation should ideally involve pathological expertise.

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Practical Takeaways

•Ganglion cytology offers a rapid alternative to standard histology for confirming grass sickness at postmortem, enabling faster outbreak diagnosis and management decisions
•May-Grünwald Giemsa staining should be the preferred staining method when resources are limited, as it provides clearer cell morphology than other stains
•This technique allows field practitioners and diagnosticians to obtain confirmatory results within hours rather than days, critical during outbreak investigations

Key Findings

•Ganglion cytology achieved 100% sensitivity and specificity for dysautonomia diagnosis when all three staining methods (MGG, HE, CFV) were examined together
•May-Grünwald Giemsa staining proved most reliable with only 11.1% of smears showing tentative diagnosis due to suboptimal morphology
•Only 3.7% of all smears (4/107) were nondiagnostic due to low cellularity, demonstrating the method's overall reliability
•Cranial cervical ganglion cytology provides rapid postmortem diagnosis compared to traditional histological examination

Conditions Studied

equine dysautonomia (grass sickness)autonomic neuronal degeneration

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