Evaluation of field-testing protocols to diagnose insulin dysregulation in ponies using a Bayesian approach.
Abstract: Field tests and their association with laminitis have not been evaluated in large cohorts. The objectives of this study were to evaluate the performance of basal insulin (BI), the oral sugar test (OST) and the insulin tolerance test (ITT) to diagnose ID and investigate their association with laminitis. Insulin dysregulation status was determined in 146 ponies using BI (insulin concentration >20 µIU/mL), an OST (insulin concentration >65 µIU/mL at 60 or 90min after oral administration of 0.45mL/kg corn syrup) and an ITT (< 50% reduction in glucose concentration 30min after intravenous administration of 0.1 IU/kg insulin). Laminitis was identified using modified-Obel scores. A Bayesian approach was used to define the characteristics of the tests and receiver operating characteristic curves were used to assess their association with laminitis. All tests were well tolerated and laminitis was diagnosed in 9% of ponies. Insulin dysregulation was diagnosed in 15% of ponies using BI, 38% using the OST and 54% using the ITT with 11% of ponies positive for all 3 tests. The sensitivities and specificities of BI, the OST and the ITT to diagnose ID were 0.52 (95% confidence interval [CI], 0.35 - 0.79) and 0.97 (95% CI, 0.91 - 1.00), 0.84 (95% CI, 0.70 - 0.94) and 0.60 (95% CI, 0.49 - 0.71), and 0.85 (95% CI, 0.68 - 0.96) and 0.88 (95% CI, 0.75 - 0.97), respectively. Only BI and the OST were associated with laminitis (P = 0.003 and 0.015, respectively).
Copyright © 2023 Elsevier Ltd. All rights reserved.
Publication Date: 2023-08-01 PubMed ID: 37536451DOI: 10.1016/j.tvjl.2023.106019Google Scholar: Lookup
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Summary
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This study is investigating a condition in ponies known as insulin dysregulation (ID), which can lead to laminitis—a painful condition in the hooves. The study aims to evaluate three diagnostic tests for ID and determine their association with laminitis.
Here’s a breakdown:
Objective:
- The study aims to evaluate three tests: basal insulin (BI), the oral sugar test (OST), and the insulin tolerance test (ITT) for their ability to diagnose insulin dysregulation (ID) in ponies.
- The study also wants to investigate if any of these tests can predict the occurrence of laminitis in ponies.
Methods:
- Sample: 146 ponies participated.
- Tests:
- BI: Measures the insulin level. A reading >20 µIU/mL indicates ID.
- OST: Measures insulin level after giving the pony corn syrup orally. A reading >65 µIU/mL at 60 or 90 minutes after indicates ID.
- ITT: Measures the drop in glucose levels after giving insulin intravenously. A drop of less than 50% in glucose level after 30 minutes indicates ID.
- Laminitis was determined using modified-Obel scores—a method to classify the severity of the condition.
Findings:
- Prevalence:
- Laminitis was found in 9% of the ponies.
- ID was found in 15% of ponies using BI, 38% using OST, and 54% using ITT. Interestingly, only 11% were positive for all three tests.
Performance of Tests:
- BI: Sensitivity was 52% and specificity was 97%.
- OST: Sensitivity was 84% and specificity was 60%.
- ITT: Sensitivity was 85% and specificity was 88%.
- Among these, only BI and OST tests showed a significant association with laminitis.
Conclusion:
- While all three tests were well-tolerated and could detect ID, only the BI and OST were significantly associated with laminitis in ponies. This suggests that they might be more useful in predicting the risk of laminitis in ponies with ID.
In simpler terms, the study found that while all three tests can detect insulin problems in ponies, only two of them (BI and OST) were associated with the actual occurrence of laminitis, a painful foot condition.
Cite This Article
APA
Clark BL, Stewart AJ, Kemp KL, Bamford NJ, Bertin FR.
(2023).
Evaluation of field-testing protocols to diagnose insulin dysregulation in ponies using a Bayesian approach.
Vet J, 106019.
https://doi.org/10.1016/j.tvjl.2023.106019 Publication
Researcher Affiliations
- The University of Queensland, 5391 Warrego Hwy, Gatton, QLD 4343, Australia. Electronic address: brianna-clark@outlook.com.
- The University of Queensland, 5391 Warrego Hwy, Gatton, QLD 4343, Australia.
- The University of Queensland, 5391 Warrego Hwy, Gatton, QLD 4343, Australia.
- The University of Melbourne, Park Drive, Parkville, VIC 3010, Australia.
- The University of Queensland, 5391 Warrego Hwy, Gatton, QLD 4343, Australia.
Conflict of Interest Statement
Conflict of interest statement None of the authors has any other financial or personal relationships that could inappropriately influence or bias the content of the paper.
Citations
This article has been cited 4 times.- Cox A, Stewart AJ. Insect Bite Hypersensitivity in Horses: Causes, Diagnosis, Scoring and New Therapies. Animals (Basel) 2023 Aug 4;13(15).
- Barnabé MA, Elliott J, Harris PA, Menzies-Gow NJ. Effects of pasture consumption and obesity on insulin dysregulation and adiponectin concentrations in UK native-breed ponies. Equine Vet J 2026 Jan;58(1):243-255.
- Kemp KL, Yuen NKY, Skinner JE, Bertin FR. Effect of Phenylbutazone Administration on Insulin Sensitivity in Horses With Insulin Dysregulation. J Vet Intern Med 2025 Mar-Apr;39(2):e70028.
- Galinelli NC, Bamford NJ, Erdody ML, Mackenzie SA, Warnken T, Harris PA, Sillence MN, Bailey SR. Effect of pergolide treatment on insulin dysregulation in horses and ponies with pituitary pars intermedia dysfunction. Equine Vet J 2025 Nov;57(6):1612-1622.
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