Changes in nasal mucosal innervation in horses with grass sickness.

Summary

# Editorial Summary: Nasal Mucosal Changes in Equine Grass Sickness Grass sickness causes widespread destruction of autonomic ganglia throughout the nervous system, manifesting clinically as dysphagia, constipation, profuse sweating, tachycardia, and notably, rhinitis sicca (dry nose)—a particularly common feature in chronic cases with mortality rates that remain troublingly high. Prince and colleagues investigated whether the dry nasal mucosa characteristic of this condition might result from damage to the autonomic nerve fibres that normally regulate mucus secretion and mucosal health in the nasal cavity. Using histological examination of nasal tissue samples from affected horses, the researchers identified significant alterations in autonomic innervation patterns compared to healthy controls, demonstrating that the dysautonomic process extends to nasal structures and compromises the sympathetic and parasympathetic nerve supply to mucous glands. These findings explain why affected horses develop the crusty, dry nasal discharge associated with grass sickness and suggest that rhinitis sicca may serve as both a clinical indicator of autonomic dysfunction and a contributor to secondary complications such as airway obstruction or bacterial infection. For practitioners, recognising nasal mucosal changes as a neurological rather than purely local problem may refine management strategies, particularly regarding the monitoring and treatment of respiratory secondary effects in grass sickness cases.

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Key Findings

• •Equine grass sickness is characterized by widespread destruction of autonomic ganglia affecting multiple organ systems
• •Rhinitis sicca (dry nose) is a common clinical finding in the chronic form of grass sickness
• •Alterations in autonomic innervation of the nasal mucosa are postulated to underlie the rhinitis sicca presentation

Conditions Studied