Severe asthma in horses is associated with increased airway innervation.
Authors: Leduc Laurence, Leclère Mathilde, Gauthier Laurie Girardot, Marcil Olivier, Lavoie Jean-Pierre
Journal: Journal of veterinary internal medicine
Summary
# Severe Asthma in Horses Associated with Increased Airway Innervation The neurological control of airways has long been recognised as a driver of asthma severity in humans, yet equivalent investigation in equine respiratory disease has been limited. Leduc and colleagues addressed this gap by examining peribronchial nerve density in lung tissue from eight asthmatic and eight healthy horses, using immunohistochemistry to visualise nerve fibres and quantify their distribution relative to airway size. Horses with severe asthma demonstrated substantially elevated nerve density in the peribronchial region—approximately 3.6 times higher than controls—alongside significantly increased nerve innervation of the airway smooth muscle layer itself. These structural changes suggest that aberrant neural remodelling may perpetuate bronchospasm and airway obstruction in equine asthma, potentially through enhanced sensory or parasympathetic signalling that amplifies smooth muscle contractility. For practitioners, these findings provide mechanistic insight supporting the use of anticholinergic or bronchodilator therapies targeting neurally-mediated airway responses, whilst highlighting that asthma severity may involve irreversible tissue remodelling beyond simple inflammatory processes—a distinction with implications for treatment intensity and prognosis in affected horses.
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Practical Takeaways
- •Asthma in horses involves structural changes in airway innervation that may explain heightened airway reactivity and reduced response to some treatments
- •Understanding that neural remodeling is part of severe asthma pathology may guide future therapeutic approaches targeting nerve signaling rather than just smooth muscle contraction
- •The association between increased innervation and asthma severity supports comprehensive management strategies for affected horses, though clinical interventions targeting innervation are not yet established
Key Findings
- •Peribronchial nerve number was 3.6-fold higher in asthmatic horses (1.87 × 10⁻⁵ nerves/μm²) compared to controls (5.17 × 10⁻⁶ nerves/μm²), P = 0.01
- •Cumulative nerve area was 2.5-fold higher in asthmatic horses (1.03 × 10⁻³ CNA/μm²) versus controls (4.14 × 10⁻⁴ CNA/μm²), P = 0.01
- •Nerves associated with airway smooth muscle were significantly increased in asthmatic horses (4.47 × 10⁻⁶ nerves/μm²) versus controls (2.26 × 10⁻⁶ nerves/μm²), P = 0.03
- •Increased airway innervation may contribute to airway smooth muscle remodeling and disease severity in equine asthma