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Ireland JL, Lester A, Banse HE. Factors affecting measurement of basal adrenocorticotropic hormone in adult domestic equids: A scoping review. Vet J 2024; 304:106071. [PMID: 38341024 DOI: 10.1016/j.tvjl.2024.106071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 01/12/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024]
Abstract
Measurement of basal adrenocorticotropic hormone (ACTH) concentration is the most commonly used diagnostic test for pituitary pars intermedia dysfunction (PPID). Although several pre-analytical and analytical factors have been reported to affect basal ACTH concentrations in equids, the extent to which these have been evaluated in the context of PPID diagnosis is unclear. The objectives of this scoping review were to identify and systematically chart current evidence about pre-analytical and analytical factors affecting basal ACTH concentrations in adult domestic equids. Systematic searches of electronic databases and conference proceedings were undertaken in June 2022, repeated in October 2022 and updated in August 2023. English language publications published prior to these dates were included. Screening and data extraction were undertaken individually by the authors, using predefined criteria and a modified scoping review data extraction template. After removal of duplicates, 903 publications were identified, of which 235 abstracts were screened for eligibility and 134 publications met inclusion criteria. Time of year, exercise, breed/type and transportation were the factors most frequently associated with significant increases in ACTH concentration (n = 26, 16, 13 and 10 publications, respectively). Only 25 publications reported inclusion of PPID cases in the study population, therefore the relationship between many factors affecting basal ACTH concentration and diagnostic accuracy for PPID remains undefined. However, several factors were identified that could impact interpretation of basal ACTH results. Findings also highlight the need for detailed reporting of pre-analytical and analytical conditions in future research to facilitate translation of evidence to practice.
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Affiliation(s)
- J L Ireland
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst CH64 7TE, Cheshire, UK.
| | - A Lester
- Department of Equine Clinical Science, Faculty of Health and Life Sciences, The University of Liverpool, Leahurst CH64 7TE, Cheshire, UK
| | - H E Banse
- School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
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Kam YN, McKenzie K, Coyle M, Bertin FR. Repeatability of a thyrotropin-releasing hormone stimulation test for diagnosis of pituitary pars intermedia dysfunction in mature horses. J Vet Intern Med 2021; 35:2885-2890. [PMID: 34642962 PMCID: PMC8692209 DOI: 10.1111/jvim.16281] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 09/27/2021] [Accepted: 10/01/2021] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Pituitary pars intermedia dysfunction (PPID) is a common endocrinopathy of horses diagnosed with a thyrotropin-releasing hormone (TRH) stimulation test. HYPOTHESIS/OBJECTIVES Describe the repeatability of TRH stimulation in horses with and without PPID in winter and autumn. ANIMALS Twenty adult horses; 6 controls and 6 with PPID tested in autumn, 8 controls and 6 with PPID tested in winter with 3 controls and 3 with PPID tested in both seasons. METHODS Thyrotropin-releasing hormone stimulation was performed on 2 consecutive occasions, 1 week before and 1 week after the winter solstice and the autumn equinox. Blood was collected before and 30 minutes after IV injection of 1 mg of TRH. ACTH concentration was determined by a chemiluminescent assay. Repeatability and test-retest reliability were assessed by repeated measures analysis of variance, intraclass correlation coefficient and within-horse coefficients of variation (CV). Bland-Altman plots were generated to visualize agreement between repetitions. RESULTS In winter, no week effect was detected on the results of the TRH simulation and the test had an excellent test-retest reliability. In autumn, after-TRH ACTH concentrations were significantly lower on week 2 (P = .02) and the test only had a good test-retest reliability. There were significantly larger within-horse CV during autumn (P = .04) and after TRH stimulation (P = .04). There were 2 misclassifications in winter and 4 in autumn. CONCLUSIONS AND CLINICAL IMPORTANCE The TRH stimulation test was repeatable when performed 2 weeks apart in winter; however, in autumn, more variability in after-TRH ACTH concentrations resulted in decreased repeatability.
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Affiliation(s)
- Yan Ning Kam
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Kelly McKenzie
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Mitchell Coyle
- Office of the Director of Gatton Campus, The University of Queensland, Gatton, Queensland, Australia
| | - François-René Bertin
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
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Changes Associated with the Peri-Ovulatory Period, Age and Pregnancy in ACTH, Cortisol, Glucose and Insulin Concentrations in Mares. Animals (Basel) 2021; 11:ani11030891. [PMID: 33804751 PMCID: PMC8003915 DOI: 10.3390/ani11030891] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 11/17/2022] Open
Abstract
Simple Summary The reproductive cycle of mares is associated with many hormonal changes, but the effects of this cycle and pregnancy on adrenocorticotropic hormone and insulin concentrations are poorly described, which could limit our ability to diagnose pituitary pars intermedia dysfunction and insulin dysregulation. In this study, healthy mares are followed through their reproductive cycle during the physiologic breeding season, and adrenocorticotropic hormone, cortisol, glucose and insulin concentrations are measured to determine the effects of age, pregnancy and the reproductive cycle on analyte concentrations. No significant effect of age, the reproductive cycle or pregnancy is detected on the cortisol, glucose or insulin concentrations; however, adrenocorticotropic hormone concentrations are significantly increased throughout the peri-ovulatory period and during pregnancy. Therefore, knowledge of a mare’s reproductive cycle might be beneficial when interpreting adrenocorticotropic hormone concentrations. Abstract Although there are many hormonal changes associated with reproduction, the effects of ovulation and early pregnancy on adrenocorticotropic hormone (ACTH) and insulin concentrations are poorly described. We hypothesise that both ovulation and early pregnancy will alter ACTH and insulin concentrations in healthy mares. Eighteen mares showing no clinical signs suggestive of, or laboratory findings consistent with, pituitary pars intermedia dysfunction PPID and insulin dysregulation (ID) are enrolled. ACTH, cortisol, insulin and glucose concentrations are measured over their peri-ovulatory period, as determined via ultrasounds and progesterone concentrations. The mares are grouped by age and gestation status, and a two-way repeated-measures ANOVA is used to determine the effects of age and early pregnancy, along with the peri-ovulatory period, on analyte concentrations. No significant effect of age, ovulation or early pregnancy is detected on the mares’ cortisol, insulin or glucose concentrations; however, there is a significant effect of early pregnancy and ovulation on ACTH concentrations (p = 0.04 and p = 0.04 respectively). ACTH concentrations change around ovulation and with early pregnancy. Therefore, knowledge of a mare’s reproductive status might be beneficial when interpreting ACTH concentrations.
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Horn R, Stewart AJ, Jackson KV, Dryburgh EL, Medina-Torres CE, Bertin FR. Clinical implications of using adrenocorticotropic hormone diagnostic cutoffs or reference intervals to diagnose pituitary pars intermedia dysfunction in mature horses. J Vet Intern Med 2020; 35:560-570. [PMID: 33368633 PMCID: PMC7848300 DOI: 10.1111/jvim.16017] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Diagnosis of pituitary pars intermedia dysfunction (PPID) is problematic because of large variations in ACTH concentrations. HYPOTHESIS/OBJECTIVES Compare the test characteristics of baseline and post-thyrotropin-releasing hormone (TRH) stimulation plasma ACTH concentrations in horses using diagnostic cutoff values (DCOVs) and reference intervals (RIs) and determine the clinical consequences of using each method. ANIMALS One hundred six mature horses: 72 control cases and 34 PPID cases. METHODS Prospective case-controlled study. Horses underwent monthly TRH stimulation tests. Diagnostic cutoff values were determined monthly by receiver operating characteristic curves using the Youden index. Reference intervals were determined monthly by a robust method. For each case age, sex and body condition score (BCS) were recorded. RESULTS Baseline ACTH concentrations varied by month (P < .001) with significant "month × age" (P = .003), "month × sex" (P = .003), and "month × BCS" (P = .007) effects. Baseline ACTH concentrations were accurate to diagnose PPID (0.91 ± 0.06) with DCOVs increasing the test sensitivity (0.61 ± 0.21 to 0.87 ± 0.05, P = .002) and RI increasing test specificity (0.85 ± 0.12 to 0.98 ± 0.01, P = .01). Thyrotropin-releasing hormone stimulation improved test accuracy (0.91 ± 0.06 to 0.97 ± 0.03, P = .004). CONCLUSIONS AND CLINICAL IMPORTANCE ACTH concentrations follow a circannual rhythm and vary with physiological factors. As using DCOVs increases the ability to detect mild cases and using RI decreases the risk of unnecessary treatments, ACTH concentrations should be interpreted within a specific clinical context. The TRH stimulation test improves the diagnosis of PPID.
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Affiliation(s)
- Remona Horn
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Allison J Stewart
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Karen V Jackson
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | | | - Carlos E Medina-Torres
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - François-René Bertin
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
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Kritchevsky JE, Muir GS, Leschke DHZ, Hodgson JK, Hess EK, Bertin FR. Blood glucose and insulin concentrations after alpha-2-agonists administration in horses with and without insulin dysregulation. J Vet Intern Med 2020; 34:902-908. [PMID: 32100334 PMCID: PMC7096659 DOI: 10.1111/jvim.15747] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 02/14/2020] [Indexed: 01/08/2023] Open
Abstract
Background In metabolically stable horses, alpha‐2‐agonists suppress insulin secretion with transient hyperglycemia and rebound hyperinsulinemia. In horses with insulin dysregulation (ID), the effect of alpha‐2‐agonists has not been investigated; however, both the alpha‐2‐agonist‐induced suppression of insulin secretion and rebound hyperinsulinemia could have clinical relevance. Hypothesis/Objectives In horses with ID, alpha‐2‐agonists will alter insulin and glucose dynamics. Animals Seven horses with ID and 7 control horses. Methods In this randomized crossover study, xylazine hydrochloride (1.1 mg/kg) or detomidine hydrochloride (30 μg/kg) were administered IV, and blood was collected for glucose and insulin concentrations at 0, 15, 30, 45, 60, 90, 120, 150, 180, and 300 minutes after administration. Horses received each drug in a random order with a 24‐hour washout period between drugs. Percent change in glucose and insulin concentrations was compared between groups, drugs, and over time with P < .05 considered significant. Results A significant time‐dependent effect of both alpha‐2‐agonists on glucose and insulin concentrations in control and ID horses was identified (P = .01 for all comparisons). There was no significant effect of sedative selection and endocrine status on blood glucose concentration in either group; however, in ID horses, xylazine administration resulted in severe rebound hyperinsulinemia whereas detomidine administration did not (P = .02). Conclusions and Clinical Importance Alpha‐2‐agonists have a significant effect on glucose and insulin concentrations in horses. In ID horses, detomidine could minimize hyperinsulinemia when compared to xylazine.
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Affiliation(s)
- Janice E Kritchevsky
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana
| | - Genevieve S Muir
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Dakota H Z Leschke
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Jack K Hodgson
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Emily K Hess
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana
| | - Francois-Rene Bertin
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
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Horn R, Bertin FR. Evaluation of combined testing to simultaneously diagnose pituitary pars intermedia dysfunction and insulin dysregulation in horses. J Vet Intern Med 2019; 33:2249-2256. [PMID: 31498947 PMCID: PMC6766519 DOI: 10.1111/jvim.15617] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 08/21/2019] [Indexed: 01/29/2023] Open
Abstract
Background The thyrotropin‐releasing hormone (TRH) stimulation test and the 2‐step insulin sensitivity test are commonly used methods to diagnose, respectively, pituitary pars intermedia dysfunction (PPID) and insulin dysregulation (ID). Objectives To investigate the diagnostic value of combining the TRH stimulation test and the 2‐step insulin sensitivity test to diagnose PPID and ID simultaneously. Animals Twenty‐seven adult horses, 10 control horses without PPID or ID, 5 horses with PPID only, 5 horses with ID only, and 7 horses with PPID and ID. Methods Randomized prospective study. Horses underwent a TRH stimulation test alone, a 2‐step insulin sensitivity test alone, and combined testing with simultaneous TRH and insulin injection in the same syringe. Data were compared by 2‐way repeated measures analysis of variance and 2 1‐sided tests to demonstrate equivalence. Bland‐Altman plots were generated to visualize agreement between combined and independent testing. Results The effect of combined testing on plasma adrenocorticotropic hormone, blood glucose concentration, or percentage decrease in blood glucose concentration was not significantly different from the effect obtained with independent testing. One control horse appeared falsely positive for PPID, 2 PPID‐only horses appeared falsely positive for ID, and 1 PPID and ID horse appeared falsely negative for ID when tests were performed simultaneously. Bland‐Altman plots supported the agreement between combined and independent testing. Conclusions and Clinical Importance Combining the TRH stimulation test and the 2‐step insulin sensitivity test appears to be a useful diagnostic tool for equine practitioners in the field, allowing testing of a horse for both PPID and ID simultaneously.
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Affiliation(s)
- Remona Horn
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - François-René Bertin
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
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Devick IF, Hendrickson DA. Left paralumbar fossa approach combined with mesocolon fenestration for bilateral equine ovariectomy. Vet Surg 2019; 48:735-741. [PMID: 30663073 DOI: 10.1111/vsu.13166] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 11/05/2018] [Accepted: 12/20/2018] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To describe a standing left paralumbar fossa approach combined with mesocolon fenestration for bilateral equine ovariectomy. STUDY DESIGN Prospective experimental clinical study. ANIMALS Four healthy client-owned mares and 1 client-owned Molly mule. METHODS Mares were restrained in standing stocks and sedated with an α2 -agonist continuous infusion to effect. The abdominal cavity was approached via a left paralumbar fossa approach, and the contralateral right ovary was accessed through an incision in the mesocolon. The location of the window was adjusted to allow triangulation, adequate visualization, and manipulation of the contralateral right ovary. Each ovarian pedicle was ligated with extracorporeal ligatures prior to sharp transection. The ovaries were dropped and left within the abdomen as part of another study. The incision in the mesocolon was closed with laparoscopic staples. Mares were monitored hourly while hospitalized, and a questionnaire was completed by the owners 90 days after surgery. RESULTS Both ovarian pedicles were successfully ligated and transected in all mares through the left paralumbar fossa approach and mesocolon fenestration. The only complications consisted of mild incisional emphysema in 2 of 5 equids, with all resolving spontaneously. All equids returned to intended use at 90 days. CONCLUSION The left paralumbar fossa approach combined with mesocolon fenestration provided adequate access to both ovaries with minimal morbidity in this small population. CLINICAL SIGNIFICANCE A unilateral left paralumbar fossa approach and fenestration of the mesocolon should be considered as an alternative to traditional approaches for bilateral laparoscopic ovariectomies in equids.
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Affiliation(s)
- Ian F Devick
- Department of Clinical Sciences, Colorado State University, Fort Collins, Colorado
| | - Dean A Hendrickson
- Department of Clinical Sciences, Colorado State University, Fort Collins, Colorado
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Horn R, Bamford NJ, Afonso T, Sutherland M, Buckerfield J, Tan RHH, Secombe CJ, Stewart AJ, Bertin FR. Factors associated with survival, laminitis and insulin dysregulation in horses diagnosed with equine pituitary pars intermedia dysfunction. Equine Vet J 2018; 51:440-445. [DOI: 10.1111/evj.13041] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 11/02/2018] [Indexed: 12/29/2022]
Affiliation(s)
- R. Horn
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - N. J. Bamford
- Faculty of Veterinary and Agricultural Sciences The University of Melbourne Werribee Victoria Australia
| | - T. Afonso
- School of Animal and Veterinary Sciences The University of Adelaide Roseworthy South Australia Australia
| | - M. Sutherland
- Gisborne Veterinary Clinic Gisborne Victoria Australia
| | | | - R. H. H. Tan
- College of Public Health, Medical and Veterinary Sciences James Cook University Townsville Queensland Australia
- Samford Valley Veterinary Hospital Samford Queensland Australia
| | - C. J. Secombe
- School of Veterinary and Life Sciences Murdoch University Perth Western Australia Australia
| | - A. J. Stewart
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - F. R. Bertin
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
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Hofberger SC, Gauff F, Thaller D, Morgan R, Keen JA, Licka TF. Assessment of tissue-specific cortisol activity with regard to degeneration of the suspensory ligaments in horses with pituitary pars intermedia dysfunction. Am J Vet Res 2018; 79:199-210. [DOI: 10.2460/ajvr.79.2.199] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Bertin FR, Laat MA. The diagnosis of equine insulin dysregulation. Equine Vet J 2017; 49:570-576. [DOI: 10.1111/evj.12703] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/16/2017] [Indexed: 12/18/2022]
Affiliation(s)
- F. R. Bertin
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - M. A. Laat
- Science and Engineering Faculty Queensland University of Technology Brisbane Queensland Australia
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Smith S, Marr C, Dunnett C, Menzies-Gow N. The effect of mare obesity and endocrine function on foal birthweight in Thoroughbreds. Equine Vet J 2016; 49:461-466. [DOI: 10.1111/evj.12645] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 10/24/2016] [Indexed: 12/25/2022]
Affiliation(s)
- S. Smith
- Rossdales Equine Hospital; Exning, Newmarket Suffolk, UK
| | - C.M. Marr
- Rossdales Equine Hospital; Exning, Newmarket Suffolk, UK
| | - C. Dunnett
- Independent Equine Nutrition; Newmarket Suffolk, UK
| | - N.J. Menzies-Gow
- Royal Veterinary College; North Mymms, Hatfield Hertfordshire UK
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