Somatotropic axis resistance and ghrelin in critically ill foals.
Authors: Barsnick R J I M, Hurcombe S D A, Dembek K, Frazer M L, Slovis N M, Saville W J A, Toribio R E
Journal: Equine veterinary journal
Summary
# Editorial Summary Critically ill neonatal foals develop resistance to the somatotropic axis—a hormonal dysfunction well-documented in human critical care but poorly characterised in equine neonates—manifesting as elevated growth hormone and ghrelin alongside suppressed insulin-like growth factor-1 (IGF-1), a pattern that correlates with disease severity and metabolic derangement. Researchers prospectively analysed blood samples from 125 foals aged less than seven days (44 septic, 62 non-septic sick, and 19 healthy controls), measuring growth hormone, ghrelin, IGF-1, glucose and triglycerides, with sepsis defined by positive blood cultures or sepsis scores ≥12. Septic foals demonstrated significantly elevated ghrelin, growth hormone and triglycerides alongside hypoglycaemia and suppressed IGF-1 compared to healthy foals, whilst the growth hormone:IGF-1 ratio—a marker of somatotropic resistance—proved predictive of survival in septic foals, with non-survivors showing paradoxically lower ratios. These findings suggest that maintaining functional somatotropic signalling may be critical for neonatal foal survival during sepsis; clinicians should recognise somatotropic resistance as a contributor to the catabolic state and metabolic dysfunction characteristic of critical illness, potentially offering targets for supportive care interventions aimed at modulating these hormonal pathways.
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Practical Takeaways
- •Recognition that critically ill foals develop somatotropic axis resistance similar to human septic patients, contributing to catabolism and poor outcomes; assessment of GH:IGF-1 ratios may help stratify mortality risk in septic foals
- •Energy metabolism dysregulation (low glucose, high triglycerides) accompanying somatotropic resistance suggests nutritional support strategies targeting these abnormalities may improve survival in neonatal foal sepsis
- •A functionally responsive somatotropic axis appears protective in foal sepsis, indicating that therapies preserving or enhancing this axis function warrant investigation as adjunctive sepsis treatments
Key Findings
- •Septic foals demonstrated somatotropic axis resistance characterized by elevated ghrelin, growth hormone, and triglycerides with decreased IGF-1 and glucose compared to healthy foals (P<0.01)
- •Growth hormone:IGF-1 ratio was significantly higher in septic and sick nonseptic foals than healthy controls (P<0.05), indicating functional axis resistance
- •In septic foals, nonsurvivors had a lower growth hormone:IGF-1 ratio than survivors (P=0.043), suggesting functional somatotropic axis activity is associated with improved outcomes
- •Somatotropic axis resistance was associated with energy metabolism abnormalities (hypoglycemia and hypertriglyceridemia) and mortality risk in critically ill foals