Recovery of insulin sensitivity in mature horses after a 3 week course of dexamethasone therapy.
Authors: Brennan K M, Urschel K L
Journal: Equine veterinary journal
Summary
# Editorial Summary Dexamethasone's immunosuppressive effects are invaluable in equine practice, yet prolonged administration consistently impairs insulin sensitivity—a concern for horses prone to laminitis and metabolic disease. Brennan and Urschel administered 0.04 mg/kg daily oral dexamethasone to eight healthy horses for 21 days, then tracked plasma glucose, insulin concentrations and insulin sensitivity markers (modified insulin-to-glucose ratio and reciprocal square root of insulin) for 22 days post-treatment using weekly baseline samples and intensive sampling immediately after cessation. Blood glucose normalised rapidly within 2 days, whilst insulin concentrations took 3 days to settle; however, the modified insulin-to-glucose ratio required 4 days to recover, and insulin sensitivity itself—the critical functional measure—did not return to baseline until day 15, indicating delayed pancreatic β-cell recovery. For practitioners using dexamethasone therapeutically, these findings suggest that metabolic monitoring should extend well beyond the visible normalisation of glucose levels, particularly in horses at risk of insulin dysregulation, and that a 2-3 week post-treatment observation window may be prudent before declaring full metabolic recovery.
Read the full abstract on PubMed
Practical Takeaways
- •When discontinuing dexamethasone in horses, expect prolonged insulin elevation and reduced insulin sensitivity for up to 2-3 weeks despite normalization of blood glucose within days
- •Monitor metabolic status beyond the first few days after stopping dexamethasone, particularly in horses at risk for laminitis or metabolic dysfunction
- •Exercise caution with feeding and management during the 2-week post-treatment recovery period, as insulin sensitivity remains compromised even when glucose appears normalized
Key Findings
- •Blood glucose returned to baseline within 2 days of dexamethasone cessation
- •Plasma insulin concentrations remained elevated until day 3 post-treatment
- •Insulin sensitivity markers required 15 days to return to baseline values, significantly longer than glucose normalization
- •Pancreatic β-cell responsiveness showed delayed recovery compared to acute glucose homeostasis