The anti-inflammatory effects of IV administered clenbuterol in horses with recurrent airway obstruction.
Authors: Laan Tamarinde T J M, Bull Sarah, Pirie R Scott, Fink-Gremmels Johanna
Journal: Veterinary journal (London, England : 1997)
Summary
Recurrent airway obstruction in horses has traditionally been managed with clenbuterol primarily for its bronchodilatory properties, yet emerging evidence suggests that cyclic AMP-elevating agents possess significant anti-inflammatory capacity alongside this recognised function. Researchers administered intravenous clenbuterol to seven RAO-susceptible horses prior to inhalation challenges using three different inflammatory triggers—lipopolysaccharide, hay dust suspension, and *Aspergillus fumigatus* antigen—to determine whether the drug could modulate the inflammatory cascade itself. Treatment with clenbuterol substantially improved lung function metrics and reduced both total bronchoalveolar lavage cell counts and neutrophil infiltration; additionally, it dampened pro-inflammatory cytokine and chemokine expression in alveolar macrophages across multiple challenge models, though interleukin-6 expression increased following exposure. These findings reframe clenbuterol as a genuine immunomodulatory agent rather than merely a smooth muscle relaxant, with meaningful implications for RAO management strategies—suggesting that the drug's therapeutic benefits extend beyond simple airway dilation to include genuine suppression of the underlying inflammatory process. For practitioners, this indicates that intravenous clenbuterol administration may offer additive clinical value in RAO cases, potentially working synergistically with environmental management and other interventions to interrupt the pathogenic inflammatory cascade.
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Practical Takeaways
- •Clenbuterol may offer dual benefits in RAO management—both bronchodilation and reduced airway inflammation—making it a valuable therapeutic option for horses with this condition
- •The drug's ability to modulate macrophage cytokine production suggests potential value in reducing recurrent flare-ups triggered by environmental allergen challenges
- •Consider IV clenbuterol administration for RAO-susceptible horses, particularly those exposed to hay dust or fungal antigens that typically trigger inflammatory responses
Key Findings
- •Intravenous clenbuterol significantly improved lung function and reduced total cell count and neutrophil influx in bronchoalveolar lavage fluid in RAO-susceptible horses
- •Clenbuterol decreased expression of pro-inflammatory cytokines and chemokines in alveolar macrophages following LPS and HDS challenges
- •Clenbuterol increased interleukin-6 expression across different antigen challenges, indicating dual pro- and anti-inflammatory modulation
- •The anti-inflammatory effects of clenbuterol provide additional therapeutic benefit beyond its recognized bronchodilatory action in equine RAO