Evaluation of basal plasma α-melanocyte-stimulating hormone and adrenocorticotrophic hormone concentrations for the diagnosis of pituitary pars intermedia dysfunction from a population of aged horses.
Abstract: The sensitivity and specificity of basal plasma α-melanocyte-stimulating hormone (α-MSH) and adrenocorticotrophic hormone (ACTH) for the diagnosis of pituitary pars intermedia dysfunction (PPID) has not been evaluated in a population-based study. Objective: To evaluate basal plasma α-MSH and ACTH concentrations for the diagnosis of PPID in a population of horses aged ≥ 15 years. Methods: Owner-reported data were obtained using a postal questionnaire distributed to an equestrian group. A subgroup of surveyed owners was visited and veterinary examination performed on horses aged ≥ 15 years. Blood samples were analysed for plasma α-MSH and ACTH concentrations. Seasonally adjusted cut-off values for α-MSH and ACTH concentrations for the diagnosis of PPID were obtained using Youden index values against a clinical gold standard diagnosis (hirsutism plus 3 or more clinical signs of PPID). Results: α-melanocyte-stimulating hormone and ACTH were highly correlated with each other and with clinical and historical indicators of PPID. The increase in both α-MSH and ACTH with increasing numbers of clinical signs in affected horses supports a spectrum of disease. Both variables were affected by season, with derived cut-off values being higher in autumn compared with other seasons. Sensitivity and specificity were moderate and good in nonautumn seasons (59 and 93%, respectively) for α-MSH using a cut-off of 52.0 pmol/l. Sensitivity and specificity were good in nonautumn seasons (80 and 83%, respectively) for ACTH using a cut-off of 29.7 pg/ml. For both α-MSH and ACTH, sensitivity and specificity were close to 100% for samples obtained during the autumn period. Conclusions: Basal plasma α-MSH and ACTH had moderate-to-good sensitivity and specificity for the diagnosis of PPID, which improved substantially during the autumn period, suggesting this may be the ideal time to test. Further studies to develop seasonally adjusted reference intervals for different geographical locations are warranted.
© 2012 EVJ Ltd.
Publication Date: 2012-05-06 PubMed ID: 22563728DOI: 10.1111/j.2042-3306.2012.00575.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Age Factors
- Blood Analysis
- Clinical Pathology
- Clinical Signs
- Clinical Study
- Diagnosis
- Diagnostic Technique
- Disease
- Disease Diagnosis
- Epidemiology
- Equine Health
- Geriatric Horses
- Hormones
- Horses
- Pituitary Pars Intermedia Dysfunction
- Plasma
- Population Dynamics
- Seasonal Variation
- Sensitivity and Specificity
- Veterinary Medicine
Summary
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The research aims to evaluate the reliability of basal plasma α-melanocyte-stimulating hormone (α-MSH) and adrenocorticotrophic hormone (ACTH) for diagnosing pituitary pars intermedia dysfunction (PPID) in horses that are 15 years and older. Their findings suggest that these hormone concentrations are highly affected by seasons, making them most accurate during autumn for diagnosing PPID.
Objectives and Methods
- The goal of the study was to examine the use of basal plasma α-MSH and ACTH to diagnose PPID in an aging horse population. PPID is a common condition in older horses that affects the pituitary gland.
- Data was collected from horse owners through a postal questionnaire which invited them for the horse’s veterinary examination.
- Further, the blood samples of horses aged 15 years and older were analysed for the concentrations of α-MSH and ACTH hormones.
- Seasonally adjusted cut-off values for these hormones that help in diagnosing PPID were obtained using the Youden index, which is a method to determine optimal cut-off points.
Results
- The findings show that α-MSH and ACTH are highly correlated with each other, as well as with clinical and historical indicators of PPID. This indicates that these hormone levels could be an effective way of diagnosing this condition.
- Through the study, it’s suggested that there’s a spectrum of PPID severity, demonstrated by the increasing hormone levels with increased clinical signs.
- Of special note, the hormone concentrations in the cattle were found to fluctuate with seasons, particularly they had higher derived cut-off values in autumn compared to other seasons.
- The sensitivity and specificity, which reflects the test accuracy, were found to be moderate to good in non-autumn seasons, while it approached 100% for samples obtained during autumn season.
Conclusions
- The study concludes that basal plasma α-MSH and ACTH have moderate-to-good sensitivity and specificity for diagnosing PPID in aged horses. These results improve significantly during the autumn season, suggesting that autumn may be the ideal time to test for PPID using this method.
- It further suggests the need for additional studies to develop seasonally adjusted reference intervals for different geographical locations, adding more versatility to this diagnostic method.
Cite This Article
APA
Mc Gowan TW, Pinchbeck GP, Mc Gowan CM.
(2012).
Evaluation of basal plasma α-melanocyte-stimulating hormone and adrenocorticotrophic hormone concentrations for the diagnosis of pituitary pars intermedia dysfunction from a population of aged horses.
Equine Vet J, 45(1), 66-73.
https://doi.org/10.1111/j.2042-3306.2012.00575.x Publication
Researcher Affiliations
- Faculty of Natural Resources, Agriculture and Veterinary Science, University of Queensland, Gatton, Australia. cmcgowan@liverpool.ac.uk
MeSH Terms
- Adrenocorticotropic Hormone / blood
- Adrenocorticotropic Hormone / genetics
- Adrenocorticotropic Hormone / metabolism
- Aging / physiology
- Animals
- Data Collection
- Horse Diseases / blood
- Horse Diseases / diagnosis
- Horse Diseases / metabolism
- Horses
- Pituitary ACTH Hypersecretion / diagnosis
- Pituitary ACTH Hypersecretion / veterinary
- Pituitary Gland, Intermediate / metabolism
- Surveys and Questionnaires
- alpha-MSH / blood
- alpha-MSH / genetics
- alpha-MSH / metabolism
Citations
This article has been cited 18 times.- Drozdzewska K, Gehlen H. Markers for internal neoplasia in the horse. Vet Med Sci 2023 Jan;9(1):132-143.
- Kirkwood NC, Hughes KJ, Stewart AJ. Prospective Case Series of Clinical Signs and Adrenocorticotrophin (ACTH) Concentrations in Seven Horses Transitioning to Pituitary Pars Intermedia Dysfunction (PPID). Vet Sci 2022 Oct 17;9(10).
- Kirkwood NC, Hughes KJ, Stewart AJ. Pituitary Pars Intermedia Dysfunction (PPID) in Horses. Vet Sci 2022 Oct 10;9(10).
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- Vaughn SA, Lemons MB, Hart KA. The Effect of Season and Breed on Hypothalamic-Pituitary-Adrenal Axis Hormones, Metabolic Hormones, and Oxidative Markers in Ponies and Horses. J Vet Intern Med 2025 Mar-Apr;39(2):e70047.
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