Metabolic Syndrome: What the Research Says
Evidence from 20 peer-reviewed studies
What Professionals Should Know
- •AMPK agonist therapy with resveratrol, metformin, or aspirin should not be relied upon as effective treatments for insulin dysregulation in horses—consider alternative therapeutic approaches
- •Horses receiving glucocorticoids require baseline metabolic testing to identify insulin dysregulation early, as 14 days of dexamethasone significantly impaired glucose regulation and caused clinical laminitis in some animals
- •The combination of three different AMPK agonists failed where individual agents might have been expected to work; current evidence does not support their use for managing metabolic syndrome in horses
- •Joint injections with triamcinolone may trigger metabolic changes that increase laminitis risk even in metabolically normal horses—consider timing and monitoring protocols
- •Monitor for clinical signs of laminitis more closely following intra-articular corticosteroid injections, particularly in horses with any metabolic predisposition
- •Alternative or adjunctive joint treatments should be considered for horses at higher laminitis risk, despite the cost and efficacy advantages of corticosteroid injections
- •Monitor vitamin D status in horses, particularly those with metabolic or endocrine disorders, as deficiency may contribute to disease pathogenesis
- •Consider seasonal variations and management factors (likely pasture turnout and sun exposure) when assessing vitamin D adequacy in individual horses
- •Further research is needed to establish optimal vitamin D supplementation strategies and target concentrations for horses
- •Obese horses with insulin dysregulation have increased clotting tendency, which may elevate thromboembolism risk—weight management and metabolic control become cardiovascular risk reduction strategies
- •Body condition assessment is relevant to thrombotic risk; horses scoring ≥7.5/9 on the Henneke scale warrant metabolic evaluation and closer clinical monitoring
- •Consider hypercoagulability as an additional systemic consequence of equine obesity and metabolic syndrome when assessing comorbidity risk in these patients
- •Overfeeding horses rapidly induces metabolic dysfunction including elevated cholesterol and insulin dysregulation within 5 months, indicating feed management is critical for metabolic health
- •Monitor blood biomarkers (cholesterol, lipoproteins, fructosamine) and glucose tolerance testing in horses receiving high-calorie diets to detect early metabolic changes before clinical disease develops
- •Restrict caloric intake in horses to prevent obesity-related metabolic complications; even moderately overweight horses (BCS 2.9) can develop significant lipid and insulin abnormalities
- •Fasting insulin and proxy calculations (particularly RISQI and QUICKI) can be reliably used to screen for insulin resistance in clinical practice, avoiding the need for expensive and time-consuming clamp testing
- •Use established cut-off values from this study when interpreting fasting insulin and proxy results to identify horses requiring dietary and management interventions for metabolic syndrome
- •Sampling on consecutive days shows good repeatability, so single-day fasting samples are adequate for clinical assessment; serial monitoring does not require multiple testing days
- •Resistin measurement may be useful as a biomarker for inflammatory status in horses with metabolic conditions, but should not be used as a standalone indicator of insulin dysregulation severity
- •Horses presenting with metabolic syndrome should be evaluated for concurrent inflammatory conditions, as resistin elevations suggest inflammation-driven pathology rather than pure metabolic dysfunction
- •Serum amyloid A measurement alongside resistin may provide complementary inflammatory markers for monitoring horses with metabolic and inflammatory disorders
- •Donkeys respond differently to glucose and insulin challenges than horses, which has implications for interpreting metabolic testing and understanding metabolic syndrome susceptibility in donkey populations
- •Baseline insulin:glucagon ratios and dynamic hormone responses documented here provide reference values for diagnostic interpretation of metabolic dysfunction in donkeys
- •The higher relative glucagon levels in donkeys may explain their greater prevalence of metabolic disorders and dyslipidaemias compared to horses, informing dietary and management strategies
- •Elevated TNF-alpha may be a useful biomarker to identify ponies at higher risk for recurrent laminitis, potentially supporting early intervention strategies
- •The association between TNF-alpha and insulin resistance suggests metabolic management targeting inflammation could help prevent laminitis in susceptible ponies
- •Standard inflammatory markers like fibrinogen may not adequately reflect laminitis risk; more specific cytokine testing may be warranted for at-risk populations
- •Laminitis risk in susceptible ponies is seasonal and linked to summer pasture; metabolic screening during winter may not identify at-risk individuals
- •Monitor blood pressure and insulin status during summer months in laminitis-prone ponies as markers of metabolic syndrome and laminitis risk
- •Pasture management and dietary restriction during summer grazing periods may be critical preventive strategies for laminitis-prone ponies
- •Screen apparently healthy ponies with high body condition and family history for prelaminitic metabolic syndrome using blood markers (triglycerides, insulin, glucose) to identify at-risk individuals before clinical disease
- •Restrict dietary starch in ponies identified with metabolic syndrome markers, as high pasture starch concentration significantly increases clinical laminitis risk
- •Use basal blood insulin and glucose ratios (RISQI, MIRG) as practical preventive diagnostic tools to guide management decisions for individual ponies at risk of pasture laminitis
- •Horses with poor insulin sensitivity may develop cardiac dysfunction affecting diastolic and systolic performance, warranting cardiac screening in metabolically compromised individuals
- •Tissue Doppler imaging appears useful for detecting myocardial changes associated with insulin resistance, though further study is needed to establish clinical thresholds
- •This pilot data suggests metabolic management to improve insulin sensitivity could have cardioprotective benefits, but larger studies are needed before changing clinical practice
- •Hyperinsulinemia causes direct lamellar tissue damage through microvascular dysfunction and complement cascade activation—this supports aggressive insulin management in metabolically predisposed horses as preventive strategy
- •Novel biomarkers (talin-1, vinculin, fibrinogen, heat shock protein 90) identified in this study may enable earlier detection of endocrinopathic laminitis before clinical signs appear
- •The tissue-specific nature of lamellar damage (absent in cardiac tissue) suggests targeted lamellar therapeutics rather than systemic interventions may be most effective
- •Metformin and sitagliptin can be safely administered together orally to horses; metformin requires more frequent dosing (shorter half-life) while sitagliptin provides sustained effect over 24 hours
- •This combination appears well-tolerated in healthy horses and may warrant consideration as a treatment option for equine insulin dysregulation, pending further efficacy studies in clinical cases
- •Current evidence is limited to pharmacokinetics in healthy horses; consult with an equine internist before using this combination in horses with metabolic disorders, as clinical effectiveness has not yet been established
- •Screen donkeys for metabolic disorders early, especially obese individuals and those with recurrent laminitis, using baseline insulin and ACTH, then dynamic tests if results are borderline
- •Be aware that donkey-specific diagnostic thresholds differ from horses—consult current donkey reference ranges rather than equine cut-off values when interpreting hormone tests
- •Expect PPID prevalence in aged donkeys; monitor for classic signs (hypertrichosis, regional adiposity, laminitis, weight loss) and use appropriate dynamic testing for diagnosis
- •Elite competition ponies are dangerously overweight, suggesting owners and judges may not recognize obesity as a problem at show level
- •Adiposity may influence judging outcomes in conformation-based competitions, creating perverse incentives to maintain excessive weight
- •Widespread obesity in competition ponies puts them at high risk for metabolic syndrome and laminitis, requiring urgent industry-wide education on healthy body condition
- •High fructan pastures (especially in spring and fall) may increase laminitis risk in susceptible horses through mechanisms involving intestinal bacteria-mediated fructose generation and hepatic metabolism
- •Managing fructan intake through grazing time restrictions, hay feeding, or pasture selection could be a preventive strategy for metabolic syndrome and laminitis-prone horses
- •Further research is needed to confirm these mechanisms before making definitive dietary recommendations, but reducing fructan exposure in horses with insulin resistance or laminitis history warrants consideration
- •Review feeding practices and exercise regimens for overweight horses, particularly those showing signs of insulin resistance, as these are modifiable risk factors for laminitis
- •Screen obese or insulin-resistant horses for EMS and monitor closely for laminitis development, which may require euthanasia in severe cases
- •Focus management on reducing sugar and starch intake while increasing physical activity to mitigate metabolic syndrome risk
- •Laminitis involves complex vascular dysfunction beyond simple inflammation; understanding venous insufficiency and thrombotic mechanisms may inform future treatment approaches
- •Metabolic syndrome management becomes increasingly important as a preventive strategy, as it appears linked to microvasculature dysfunction in the laminae
- •Current therapeutic strategies remain limited; this review highlights the need for novel interventions targeting vascular dysfunction rather than inflammation alone
- •Screen horses for metabolic syndrome components (obesity, elevated insulin, triglycerides) as these increase laminitis risk—early identification enables preventive management
- •Weight management and insulin resistance control may reduce laminitis predisposition in affected horses, though specific mechanisms require further research
- •Consider inflammatory and vascular dysfunction pathways when managing laminitis in metabolically compromised horses, not just mechanical load factors
Key Research Findings
Dexamethasone administration for 14 days significantly altered insulin and glucose dynamics (SI, DI, basal glucose and insulin levels) and induced clinical laminitis in 15% (5/33) of horses
Combination therapy with resveratrol, metformin, and aspirin did not significantly improve insulin and glucose dynamics in horses with experimentally induced insulin dysregulation
AMPK agonists including resveratrol, metformin, and aspirin were ineffective at reversing experimentally induced metabolic dysfunction in horses
Intra-articular triamcinolone acetonide injection increases systemic insulin and glucose concentrations in horses
Hyperinsulinaemia occurs post-injection, which may increase laminitis risk
Effects observed in horses without pre-existing insulin dysregulation
Corticosteroid response mirrors metabolic changes seen in humans with metabolic syndrome
Vitamin D deficiency is common in horses and associations with endocrine diseases warrant investigation
Season, management practices, and endocrinopathies significantly influence circulating vitamin D concentrations in horses
The relative contributions of dietary intake versus skin synthesis to vitamin D status in horses remain poorly characterized
Obese, insulin-dysregulated horses showed significantly elevated thromboelastography MA values (69.5 vs 64.8 mm, P=0.007) compared to healthy controls
G-value (clot stiffness) was significantly higher in obese horses (11,749 vs 9,319 dyn/m², P=0.004), indicating increased coagulation potential
Positive correlations existed between body condition score and both MA (R=0.45, P=0.01) and G-value (R=0.46, P=0.01)
Serum insulin levels at multiple timepoints correlated with MA and G-value, suggesting insulin dysregulation drives hypercoagulability
9 horses fed a hypercaloric diet for 5 months showed significant increases in cholesterol, LDL, HDL, and fructosamine concentrations (P < 0.001)
Evidence Base
Effect of 5'-adenosine monophosphate-activated protein kinase agonists on insulin and glucose dynamics in experimentally induced insulin dysregulation in horses.
Pinnell Erin F, Hostnik Laura D, Watts Mauria R et al. (2024) — Journal of veterinary internal medicine
Intra-articular triamcinolone acetonide injection results in increases in systemic insulin and glucose concentrations in horses without insulin dysregulation.
Boger Brooke L, Manfredi Jane M, Loucks Abigail R et al. (2024) — Equine veterinary journal
The effect of season, management and endocrinopathies on vitamin D status in horses.
Dosi Miranda C M C, McGorum Bruce C, Kirton Roxane D et al. (2023) — Equine veterinary journal
Thromboelastography in obese horses with insulin dysregulation compared to healthy controls.
Lovett Amy L, Gilliam Lyndi L, Sykes Benjamin W et al. (2022) — Journal of veterinary internal medicine
Changes in metabolic and physiological biomarkers in Mangalarga Marchador horses with induced obesity.
Ribeiro Rodrigo M, Ribeiro Debora S, Cota Leticia O et al. (2021) — Veterinary journal (London, England : 1997)
Evaluation of fasting plasma insulin and proxy measurements to assess insulin sensitivity in horses.
Lindåse Sanna, Nostell Katarina, Bergsten Peter et al. (2021) — BMC veterinary research
Measurement of Plasma Resistin Concentrations in Horses with Metabolic and Inflammatory Disorders.
Fuentes-Romero Beatriz, Muñoz-Prieto Alberto, Cerón José J et al. (2021) — Animals : an open access journal from MDPI
Effect of intravenous glucose and combined glucose-insulin challenges on energy-regulating hormones concentrations in donkeys.
Mendoza F J, Gonzalez-Cara C A, Aguilera-Aguilera R et al. (2018) — Veterinary journal (London, England : 1997)
Inflammatory and redox status of ponies with a history of pasture-associated laminitis.
Treiber, Carter, Gay et al. (2009) — Veterinary immunology and immunopathology
Hypertension and insulin resistance in a mixed-breed population of ponies predisposed to laminitis.
Bailey, Habershon-Butcher, Ransom et al. (2008) — American journal of veterinary research
Evaluation of genetic and metabolic predispositions and nutritional risk factors for pasture-associated laminitis in ponies.
Treiber, Kronfeld, Hess et al. (2006) — Journal of the American Veterinary Medical Association
Investigating the Relationship Between Cardiac Function and Insulin Sensitivity in Horses: A Pilot Study.
Williams Natasha J, Furr Martin, Navas de Solis Cristobal et al. (2022) — Frontiers in veterinary science
Differential Proteomic Expression of Equine Cardiac and Lamellar Tissue During Insulin-Induced Laminitis.
Campolo Allison, Frantz Matthew W, de Laat Melody A et al. (2020) — Frontiers in veterinary science
Pharmacokinetics of Metformin in Combination With Sitagliptin in Adult Horses After Enteral Administration.
Cárceles-Rodríguez Carlos M, Fernández-Varón Emilio, Martín-Gimenez Tamara et al. (2019) — Journal of equine veterinary science
Metabolic and Endocrine Insights in Donkeys.
Mendoza Francisco J, Toribio Ramiro E, Perez-Ecija Alejandro (2024) — Animals : an open access journal from MDPI
Visual Assessment of Adiposity in Elite Hunter Ponies.
Pratt-Phillips S, Munjizun A, Janicki K (2023) — Journal of equine veterinary science
Fructokinase, Fructans, Intestinal Permeability, and Metabolic Syndrome: An Equine Connection?
Johnson Richard J, Rivard Chris, Lanaspa Miguel A et al. (2013) — Journal of equine veterinary science
Diabetes, Insulin Resistance, and Metabolic Syndrome in Horses
Philip Johnson, C. Wiedmeyer, A. Lacarrubba et al. (2012) — Journal of Diabetes Science and Technology
Equine laminitis: a journey to the dark side of venous.
Robertson, Bailey, Peroni (2009) — Veterinary immunology and immunopathology
Metabolic syndrome-From human organ disease to laminar failure in equids.
Geor, Frank (2009) — Veterinary immunology and immunopathology