Comparison of efficacy and tolerability of isoflupredone and dexamethasone in the treatment of horses affected with recurrent airway obstruction ('heaves').
Authors: Picandet V, Léguillette R, Lavoie J P
Journal: Equine veterinary journal
Summary
# Editorial Summary: Isoflupredone versus Dexamethasone for Equine Recurrent Airway Obstruction Corticosteroids remain the gold standard for managing horses with recurrent airway obstruction (RAO or 'heaves'), yet comparative data on different agents are sparse. Picandet and colleagues conducted a 35-day controlled trial comparing intramuscular isoflupredone acetate (0.03 mg/kg once daily) with intravenous dexamethasone (0.04 mg/kg once daily) in six affected horses per group, measuring lung function, endocrine and electrolyte status, adrenocorticotropic hormone (ACTH) responsiveness, and haematological parameters throughout treatment and a seven-day washout phase. Both corticosteroids significantly improved lung function by day 3 and sustained this benefit through the washout period, with suppressed resting cortisol levels yet preserved ACTH stimulation response in both groups; however, whilst dexamethasone maintained normal serum electrolyte concentrations, isoflupredone-treated horses developed clinically significant hypokalaemia, and both drugs induced expected stress-related haematological changes. For practitioners selecting between these corticosteroids, isoflupredone offers comparable therapeutic efficacy to dexamethasone for RAO management, but the hypokalaemia risk warrants serum potassium monitoring and potentially supplementation, particularly in horses with pre-existing electrolyte imbalances or those at risk of myopathic complications.
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Practical Takeaways
- •Isoflupredone is as effective as dexamethasone for treating heaves, offering an alternative corticosteroid option with comparable clinical outcomes
- •If isoflupredone is selected, monitor serum potassium levels as hypokalaemia is an associated side effect despite absence of clinical signs in this study
- •Both drugs show rapid efficacy (improvement by Day 3) and can be used clinically, but choice may depend on electrolyte stability requirements and route of administration preference
Key Findings
- •Both isoflupredone acetate (0.03 mg/kg i.m.) and dexamethasone (0.04 mg/kg i.v.) significantly improved lung function starting on Day 3 of treatment
- •Isoflupredone demonstrated equivalent therapeutic efficacy to dexamethasone for heaves management
- •Isoflupredone treatment caused significant hypokalaemia (decreased serum potassium), whereas dexamethasone did not affect serum electrolytes
- •Both corticosteroids suppressed blood cortisol levels during treatment while preserving normal ACTH response