Biochemical indices of vascular function, glucose metabolism and oxidative stress in horses with equine Cushing's disease.
Authors: Keen J A, McLaren M, Chandler K J, McGorum B C
Journal: Equine veterinary journal
Summary
# Editorial Summary Equine Cushing's disease (ECD) carries a well-documented risk of laminitis, yet the underlying biochemical mechanisms remain unclear; Keen and colleagues investigated whether glucose metabolism abnormalities and oxidative stress—similar to those driving microvascular dysfunction in diabetic humans—might explain this predisposition. Using dexamethasone suppression testing and clinical assessment, they stratified 31 aged horses into three groups: clinical ECD with hirsutism (n=12), subclinical ECD with positive DST but no hirsutism (n=10), and healthy controls (n=9), measuring glucose, insulin, plasma thiols and albumin-corrected thiol levels from single morning blood samples. Horses with overt clinical disease showed significantly elevated fasting glucose and insulin concentrations compared to both subclinical and control groups, whilst both clinical and subclinical ECD groups displayed markedly reduced plasma thiol levels indicating systemic oxidative stress. These findings suggest that glucose dysregulation and oxidative stress in ECD could precipitate laminitis through mechanisms analogous to diabetic microvascular disease, though the study's failure to detect differences in direct vascular function markers limits their diagnostic utility as preclinical indicators of dysfunction.
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Practical Takeaways
- •ECD horses with hirsutism and abnormal glucose metabolism are at higher risk of laminitis; blood glucose and insulin testing may help identify high-risk individuals for preventive management
- •Oxidative stress markers are present even in subclinical ECD, suggesting early intervention and antioxidant strategies may be warranted before clinical signs develop
- •Current vascular function tests cannot reliably predict which ECD horses will develop laminitis, so clinical monitoring and metabolic management remain essential rather than relying on single biomarkers
Key Findings
- •Horses with clinical ECD (Group 1, n=12) had significantly elevated glucose and insulin levels compared to subclinical ECD and control groups
- •Both clinical and subclinical ECD groups showed significantly lower plasma thiol levels indicating oxidative stress compared to controls
- •No significant inter-group differences were found in biochemical indices of vascular function, limiting their use as preclinical diagnostic markers
- •Glucose metabolism abnormalities and oxidative stress in ECD may contribute to laminitis development through mechanisms similar to diabetic microvascular dysfunction in humans