FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Journal of veterinary internal medicine2020; 35(1); 560-570; doi: 10.1111/jvim.16017

Clinical implications of using adrenocorticotropic hormone diagnostic cutoffs or reference intervals to diagnose pituitary pars intermedia dysfunction in mature horses.

Abstract: Diagnosis of pituitary pars intermedia dysfunction (PPID) is problematic because of large variations in ACTH concentrations. Objective: 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. Methods: 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: 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.
© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC. on behalf of the American College of Veterinary Internal Medicine.
Get Full Text
Publication Date: 2020-12-24 PubMed ID: 33368633PubMed Central: PMC7848300DOI: 10.1111/jvim.16017Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article explores ways to improve the diagnosis of Pituitary Pars Intermedia Dysfunction (PPID) in horses through the testing of plasma ACTH (Adrenocorticotropic Hormone) concentrations, taking into account monthly variations and the effects of age, sex, and body condition.

Objective and Methodology

Researchers aimed to compare the effectiveness of utilizing two diagnostic methods: Diagnostic Cutoff Values (DCOVs) and Reference Intervals (RIs), over monthly intervals. They also sought to understand the implications of using both methods in a clinical setting, analyzing how each would affect PPID diagnosis.

The study involved 106 mature horses divided into two groups, a control group of 72 horses and a group of 34 PPID-affected horses. By performing monthly Thyrotropin-Releasing Hormone (TRH) stimulation tests, researchers could track changes in ACTH concentrations. For data analysis, they used the Youden index in Receiver Operating Characteristic curves to determine DCOVs and a robust method for RIs.

Results

An emergent trend indicated that baseline ACTH concentrations varied significantly from month to month, with notable interaction effects relation to:

  • Month and age
  • Month and sex
  • Month and body condition score (BCS)

In terms of diagnostic efficiency, baseline ACTH concentrations were found to be a reliable indicator for diagnosing PPID. Using DCOVs, test sensitivity improved considerably, which means the ability of the test to accurately identify PPID-affected horses increased. Applying RIs, on the other hand, enhanced the test’s ability to correctly identify horses without PPID, thereby reducing the possibility of unnecessary treatments.

Amplifying the effects, the use of TRH stimulation resulted in a substantial improvement in test accuracy, further validating its application in diagnosing PPID.

Conclusions

The study concluded that diagnosing PPID in horses using ACTH concentrations must take into account various factors, such as the month of testing and horse-specific characteristics, including age, sex, and body condition. Further, the choice between DCOVs and RIs should be based on the specific clinical context, as both methods have their respective benefits: DCOVs are more suited for detecting mild cases, while RIs help avoid unnecessary treatments. The TRH stimulation test was recommended for its ability to enhance diagnostic accuracy.

Cite This Article

APA
Horn R, Stewart AJ, Jackson KV, Dryburgh EL, Medina-Torres CE, Bertin FR. (2020). Clinical implications of using adrenocorticotropic hormone diagnostic cutoffs or reference intervals to diagnose pituitary pars intermedia dysfunction in mature horses. J Vet Intern Med, 35(1), 560-570. https://doi.org/10.1111/jvim.16017

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 35
Issue: 1
Pages: 560-570

Researcher Affiliations

Horn, Remona
  • School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia.
Stewart, Allison J
  • School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia.
Jackson, Karen V
  • School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia.
Dryburgh, Elizabeth L
  • Boehringer Ingelheim Pty Ltd, North Ryde, New South Wales, Australia.
Medina-Torres, Carlos E
  • School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia.
Bertin, François-René
  • School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia.

MeSH Terms

  • Adrenocorticotropic Hormone / metabolism
  • Animals
  • Horse Diseases / diagnosis
  • Horses
  • Pituitary Diseases / diagnosis
  • Pituitary Diseases / veterinary
  • Pituitary Gland, Intermediate
  • Prospective Studies
  • Thyrotropin-Releasing Hormone

Grant Funding

  • Boehringer Ingelheim Pty Ltd
  • The University of Queensland

Conflict of Interest Statement

Elizabeth L. Dryburgh is employed by Boehringer‐Ingelheim Pty Ltd and François‐Rene Bertin and Allison J. Stewart have consulted for Boehringer‐Ingelheim Pty Ltd.

References

This article includes 57 references
  1. McGowan TW, Pinchbeck GP, McGowan CM. Prevalence, risk factors and clinical signs predictive for equine pituitary pars intermedia dysfunction in aged horses.. Equine Vet J 2013 Jan;45(1):74-9.
    pubmed: 22594955doi: 10.1111/j.2042-3306.2012.00578.xgoogle scholar: lookup
  2. Ireland JL, McGowan CM. Epidemiology of pituitary pars intermedia dysfunction: A systematic literature review of clinical presentation, disease prevalence and risk factors.. Vet J 2018 May;235:22-33.
    pubmed: 29704935doi: 10.1016/j.tvjl.2018.03.002google scholar: lookup
  3. Miller MA, Moore GE, Bertin FR, Kritchevsky JE. What's New in Old Horses? Postmortem Diagnoses in Mature and Aged Equids.. Vet Pathol 2016 Mar;53(2):390-8.
    pubmed: 26459516doi: 10.1177/0300985815608674google scholar: lookup
  4. 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 2019 Jul;51(4):440-445.
    pubmed: 30417404doi: 10.1111/evj.13041google scholar: lookup
  5. Rohrbach BW, Stafford JR, Clermont RS, Reed SM, Schott HC 2nd, Andrews FM. Diagnostic frequency, response to therapy, and long-term prognosis among horses and ponies with pituitary par intermedia dysfunction, 1993-2004.. J Vet Intern Med 2012 Jul-Aug;26(4):1027-34.
    pubmed: 22524260doi: 10.1111/j.1939-1676.2012.00932.xgoogle scholar: lookup
  6. Schott HC 2nd. Pituitary pars intermedia dysfunction: equine Cushing's disease.. Vet Clin North Am Equine Pract 2002 Aug;18(2):237-70.
    pubmed: 15635907doi: 10.1016/s0749-0739(02)00018-4google scholar: lookup
  7. Miller MA, Pardo ID, Jackson LP, Moore GE, Sojka JE. Correlation of pituitary histomorphometry with adrenocorticotrophic hormone response to domperidone administration in the diagnosis of equine pituitary pars intermedia dysfunction.. Vet Pathol 2008 Jan;45(1):26-38.
    pubmed: 18192571doi: 10.1354/vp.45-1-26google scholar: lookup
  8. McFarlane D, Miller LM, Craig LE, Dybdal NO, Habecker PL, Miller MA, Patterson JS, Cribb AE. Agreement in histologic assessments of the pituitary pars intermedia in aged horses.. Am J Vet Res 2005 Dec;66(12):2055-9.
    pubmed: 16379646doi: 10.2460/ajvr.2005.66.2055google scholar: lookup
  9. Alexander SL, Irvine CH. The effect of social stress on adrenal axis activity in horses: the importance of monitoring corticosteroid-binding globulin capacity.. J Endocrinol 1998 Jun;157(3):425-32.
    pubmed: 9691975doi: 10.1677/joe.0.1570425google scholar: lookup
  10. Alexander SL, Irvine CH, Livesey JH, Donald RA. Effect of isolation stress on concentrations of arginine vasopressin, alpha-melanocyte-stimulating hormone and ACTH in the pituitary venous effluent of the normal horse.. J Endocrinol 1988 Mar;116(3):325-34.
    pubmed: 2832503doi: 10.1677/joe.0.1160325google scholar: lookup
  11. Alexander SL, Irvine CH, Ellis MJ, Donald RA. The effect of acute exercise on the secretion of corticotropin-releasing factor, arginine vasopressin, and adrenocorticotropin as measured in pituitary venous blood from the horse.. Endocrinology 1991 Jan;128(1):65-72.
    pubmed: 1846116doi: 10.1210/endo-128-1-65google scholar: lookup
  12. Copas VE, Durham AE. Circannual variation in plasma adrenocorticotropic hormone concentrations in the UK in normal horses and ponies, and those with pituitary pars intermedia dysfunction.. Equine Vet J 2012 Jul;44(4):440-3.
    pubmed: 21848531doi: 10.1111/j.2042-3306.2011.00444.xgoogle scholar: lookup
  13. Jacob SI, Geor RJ, Weber PSD, Harris PA, McCue ME. Effect of dietary carbohydrates and time of year on ACTH and cortisol concentrations in adult and aged horses.. Domest Anim Endocrinol 2018 Apr;63:15-22.
    pubmed: 29195115doi: 10.1016/j.domaniend.2017.10.005google scholar: lookup
  14. Stewart AJ, Hackett E, Bertin FR, Towns TJ. Cortisol and adrenocorticotropic hormone concentrations in horses with systemic inflammatory response syndrome.. J Vet Intern Med 2019 Sep;33(5):2257-2266.
    pmc: PMC6766528pubmed: 31512777doi: 10.1111/jvim.15620google scholar: lookup
  15. Beech J, Boston R, Lindborg S, Russell GE. Adrenocorticotropin concentration following administration of thyrotropin-releasing hormone in healthy horses and those with pituitary pars intermedia dysfunction and pituitary gland hyperplasia.. J Am Vet Med Assoc 2007 Aug 1;231(3):417-26.
    pubmed: 17669045doi: 10.2460/javma.231.3.417google scholar: lookup
  16. Frank N, Andrews FM, Sommardahl CS, Eiler H, Rohrbach BW, Donnell RL. Evaluation of the combined dexamethasone suppression/ thyrotropin-releasing hormone stimulation test for detection of pars intermedia pituitary adenomas in horses.. J Vet Intern Med 2006 Jul-Aug;20(4):987-93.
    pubmed: 16955827doi: 10.1892/0891-6640(2006)20[987:eotcdt]2.0.co;2google scholar: lookup
  17. 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 Sep;33(5):2249-2256.
    pmc: PMC6766519pubmed: 31498947doi: 10.1111/jvim.15617google scholar: lookup
  18. Diez de Castro E, Lopez I, Cortes B, Pineda C, Garfia B, Aguilera-Tejero E. Influence of feeding status, time of the day, and season on baseline adrenocorticotropic hormone and the response to thyrotropin releasing hormone-stimulation test in healthy horses.. Domest Anim Endocrinol 2014 Jul;48:77-83.
    pubmed: 24906932doi: 10.1016/j.domaniend.2014.02.004google scholar: lookup
  19. Funk RA, Stewart AJ, Wooldridge AA, Kwessi E, Kemppainen RJ, Behrend EN, Zhong Q, Johnson AK. Seasonal changes in plasma adrenocorticotropic hormone and α-melanocyte-stimulating hormone in response to thyrotropin-releasing hormone in normal, aged horses.. J Vet Intern Med 2011 May-Jun;25(3):579-85.
    pubmed: 21457320doi: 10.1111/j.1939-1676.2011.0712.xgoogle scholar: lookup
  20. Bertin FR, Pader KS, Lescun TB, Sojka-Kritchevsky JE. Short-term effect of ovariectomy on measures of insulin sensitivity and response to dexamethasone administration in horses.. Am J Vet Res 2013 Dec;74(12):1506-13.
    pubmed: 24274888doi: 10.2460/ajvr.74.12.1506google scholar: lookup
  21. Borer-Weir KE, Menzies-Gow NJ, Bailey SR, Harris PA, Elliott J. Seasonal and annual influence on insulin and cortisol results from overnight dexamethasone suppression tests in normal ponies and ponies predisposed to laminitis.. Equine Vet J 2013 Nov;45(6):688-93.
    pubmed: 23521139doi: 10.1111/evj.12053google scholar: lookup
  22. Beech J, McFarlane D, Lindborg S, Sojka JE, Boston RC. α-Melanocyte--stimulating hormone and adrenocorticotropin concentrations in response to thyrotropin-releasing hormone and comparison with adrenocorticotropin concentration after domperidone administration in healthy horses and horses with pituitary pars intermedia dysfunction.. J Am Vet Med Assoc 2011 May 15;238(10):1305-15.
    pubmed: 21568777doi: 10.2460/javma.238.10.1305google scholar: lookup
  23. Beech J, Boston RC, McFarlane D, Lindborg S. Evaluation of plasma ACTH, alpha-melanocyte-stimulating hormone, and insulin concentrations during various photoperiods in clinically normal horses and ponies and those with pituitary pars intermedia dysfunction.. J Am Vet Med Assoc 2009 Sep 15;235(6):715-22.
    pubmed: 19751169doi: 10.2460/javma.235.6.715google scholar: lookup
  24. Cordero M, Brorsen BW, McFarlane D. Circadian and circannual rhythms of cortisol, ACTH, and α-melanocyte-stimulating hormone in healthy horses.. Domest Anim Endocrinol 2012 Nov;43(4):317-24.
    pubmed: 22717182doi: 10.1016/j.domaniend.2012.05.005google scholar: lookup
  25. Donaldson MT, McDonnell SM, Schanbacher BJ, Lamb SV, McFarlane D, Beech J. Variation in plasma adrenocorticotropic hormone concentration and dexamethasone suppression test results with season, age, and sex in healthy ponies and horses.. J Vet Intern Med 2005 Mar-Apr;19(2):217-22.
    pubmed: 15822567doi: 10.1892/0891-6640(2005)19<217:vipahc>2.0.co;2google scholar: lookup
  26. Mc Gowan TW, Pinchbeck GP, Mc Gowan CM. 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 2013 Jan;45(1):66-73.
    pubmed: 22563728doi: 10.1111/j.2042-3306.2012.00575.xgoogle scholar: lookup
  27. Secombe CJ, Tan RHH, Perara DI, Byrne DP, Watts SP, Wearn JG. The Effect of Geographic Location on Circannual Adrenocorticotropic Hormone Plasma Concentrations in Horses in Australia.. J Vet Intern Med 2017 Sep;31(5):1533-1540.
    pmc: PMC5598888pubmed: 28661009doi: 10.1111/jvim.14782google scholar: lookup
  28. Couëtil L, Paradis MR, Knoll J. Plasma adrenocorticotropin concentration in healthy horses and in horses with clinical signs of hyperadrenocorticism.. J Vet Intern Med 1996 Jan-Feb;10(1):1-6.
    pubmed: 8965262doi: 10.1111/j.1939-1676.1996.tb02016.xgoogle scholar: lookup
  29. Secombe C, Bailey S, de Laat M, Hughes K, Stewart A, Sonis J, Tan R. Re: Recommendations from the Australian and New Zealand Equine Endocrine Group and the interpretation of plasma endogenous ACTH concentrations for the diagnosis of pituitary pars intermedia dysfunction (PPID).. Aust Vet J 2018 Sep;96(9):319.
    pubmed: 30152059doi: 10.1111/avj.12744google scholar: lookup
  30. Bamford NJ, Harris PA, Bailey SR. Circannual variation in plasma adrenocorticotropic hormone concentrations and dexamethasone suppression test results in Standardbred horses, Andalusian horses and mixed-breed ponies.. Aust Vet J 2020 Dec;98(12):616-621.
    pubmed: 33001453doi: 10.1111/avj.13022google scholar: lookup
  31. Byrne DP, Secombe CJ, Tan RHH, Perera DI, Watts SP, Wearn JG. Circannual variability in adrenocorticotropic hormone responses to administration of thyrotropin-releasing hormone in clinically normal horses in Australia.. Vet J 2018 Aug;238:58-62.
    pubmed: 30103916doi: 10.1016/j.tvjl.2018.07.008google scholar: lookup
  32. Hu K, Stewart AJ, Yuen KY, Hinrichsen S, Dryburgh EL, Bertin FR. The effect of freeze-thaw cycles on determination of immunoreactive plasma adrenocorticotrophic hormone concentrations in horses.. J Vet Intern Med 2020 May;34(3):1350-1356.
    pmc: PMC7255672pubmed: 32255541doi: 10.1111/jvim.15771google scholar: lookup
  33. Henneke DR, Potter GD, Kreider JL, Yeates BF. Relationship between condition score, physical measurements and body fat percentage in mares.. Equine Vet J 1983 Oct;15(4):371-2.
    pubmed: 6641685doi: 10.1111/j.2042-3306.1983.tb01826.xgoogle scholar: lookup
  34. Friedrichs KR, Harr KE, Freeman KP, Szladovits B, Walton RM, Barnhart KF, Blanco-Chavez J. ASVCP reference interval guidelines: determination of de novo reference intervals in veterinary species and other related topics.. Vet Clin Pathol 2012 Dec;41(4):441-53.
    pubmed: 23240820doi: 10.1111/vcp.12006google scholar: lookup
  35. Grimes DA, Schulz KF. Refining clinical diagnosis with likelihood ratios.. Lancet 2005 Apr 23-29;365(9469):1500-5.
    pubmed: 15850636doi: 10.1016/S0140-6736(05)66422-7google scholar: lookup
  36. Swets JA. Measuring the accuracy of diagnostic systems.. Science 1988 Jun 3;240(4857):1285-93.
    pubmed: 3287615doi: 10.1126/science.3287615google scholar: lookup
  37. Boswell T, Woods SC, Kenagy GJ. Seasonal changes in body mass, insulin, and glucocorticoids of free-living golden-mantled ground squirrels.. Gen Comp Endocrinol 1994 Dec;96(3):339-46.
    pubmed: 7883140doi: 10.1006/gcen.1994.1189google scholar: lookup
  38. Robie SM, Janson CH, Smith SC, O'Connor JT Jr. Equine serum lipids: serum lipids and glucose in Morgan and Thoroughbred horses and Shetland ponies.. Am J Vet Res 1975 Dec;36(12):1705-8.
    pubmed: 1200441
  39. McGowan C. Recommendations from the Australian and New Zealand Equine Endocrine Group and the interpretation of plasma endogenous ACTH concentrations for the diagnosis of pituitary pars intermedia dysfunction (PPID).. Aust Vet J 2018 Sep;96(9):317-318.
    pubmed: 30152062doi: 10.1111/avj.12743google scholar: lookup
  40. Liburt NR, McKeever KH, Malinowski K, Smarsh DN, Geor RJ. Response of the hypothalamic-pituitary-adrenal axis to stimulation tests before and after exercise training in old and young Standardbred mares.. J Anim Sci 2013 Nov;91(11):5208-19.
    pubmed: 24045480doi: 10.2527/jas.2013-6329google scholar: lookup
  41. Keen JA, McLaren M, Chandler KJ, McGorum BC. Biochemical indices of vascular function, glucose metabolism and oxidative stress in horses with equine Cushing's disease.. Equine Vet J 2004 Apr;36(3):226-9.
    pubmed: 15147129doi: 10.2746/0425164044877215google scholar: lookup
  42. McFarlane D, Dybdal N, Donaldson MT, Miller L, Cribb AE. Nitration and increased alpha-synuclein expression associated with dopaminergic neurodegeneration in equine pituitary pars intermedia dysfunction.. J Neuroendocrinol 2005 Feb;17(2):73-80.
    pubmed: 15796757doi: 10.1111/j.1365-2826.2005.01277.xgoogle scholar: lookup
  43. Ousey JC. Peripartal endocrinology in the mare and foetus.. Reprod Domest Anim 2004 Aug;39(4):222-31.
    pubmed: 15225275doi: 10.1111/j.1439-0531.2004.00507.xgoogle scholar: lookup
  44. Cudd TA, LeBlanc M, Silver M, Norman W, Madison J, Keller-Wood M, Wood CE. Ontogeny and ultradian rhythms of adrenocorticotropin and cortisol in the late-gestation fetal horse.. J Endocrinol 1995 Feb;144(2):271-83.
    pubmed: 7706980doi: 10.1677/joe.0.1440271google scholar: lookup
  45. Jones CT, Gu W, Parer JT. Production of corticotrophin releasing hormone by the sheep placenta in vivo.. J Dev Physiol 1989 Feb;11(2):97-101.
    pubmed: 2789246
  46. Ellis MJ, Livesey JH, Donald RA. Horse plasma corticotrophin-releasing hormone (CRH): characterisation and lack of a late gestational rise or a plasma CRH-binding protein.. J Endocrinol 1994 Dec;143(3):455-60.
    pubmed: 7836890doi: 10.1677/joe.0.1430455google scholar: lookup
  47. Donaldson MT, McFarlane D, Jorgensen AJ, Beech J. Correlation between plasma alpha-melanocyte-stimulating hormone concentration and body mass index in healthy horses.. Am J Vet Res 2004 Nov;65(11):1469-73.
    pubmed: 15566082doi: 10.2460/ajvr.2004.65.1469google scholar: lookup
  48. Seeley RJ, Yagaloff KA, Fisher SL, Burn P, Thiele TE, van Dijk G, Baskin DG, Schwartz MW. Melanocortin receptors in leptin effects.. Nature 1997 Nov 27;390(6658):349.
    pubmed: 9389472doi: 10.1038/37016google scholar: lookup
  49. Kearns CF, McKeever KH, Roegner V, Brady SM, Malinowski K. Adiponectin and leptin are related to fat mass in horses.. Vet J 2006 Nov;172(3):460-5.
    pubmed: 15996495doi: 10.1016/j.tvjl.2005.05.002google scholar: lookup
  50. Fitzgerald BP, McManus CJ. Photoperiodic versus metabolic signals as determinants of seasonal anestrus in the mare.. Biol Reprod 2000 Jul;63(1):335-40.
    pubmed: 10859276doi: 10.1095/biolreprod63.1.335google scholar: lookup
  51. Norton EM, Avila F, Schultz NE, Mickelson JR, Geor RJ, McCue ME. Evaluation of an HMGA2 variant for pleiotropic effects on height and metabolic traits in ponies.. J Vet Intern Med 2019 Mar;33(2):942-952.
    pmc: PMC6430908pubmed: 30666754doi: 10.1111/jvim.15403google scholar: lookup
  52. Dybdal NO, Hargreaves KM, Madigan JE, Gribble DH, Kennedy PC, Stabenfeldt GH. Diagnostic testing for pituitary pars intermedia dysfunction in horses.. J Am Vet Med Assoc 1994 Feb 15;204(4):627-32.
    pubmed: 8163420
  53. McFarlane D, Beech J, Cribb A. Alpha-melanocyte stimulating hormone release in response to thyrotropin releasing hormone in healthy horses, horses with pituitary pars intermedia dysfunction and equine pars intermedia explants.. Domest Anim Endocrinol 2006 May;30(4):276-88.
    pubmed: 16115743doi: 10.1016/j.domaniend.2005.07.005google scholar: lookup
  54. Fagan TJ. Letter: Nomogram for Bayes's theorem.. N Engl J Med 1975 Jul 31;293(5):257.
    pubmed: 1143310doi: 10.1056/NEJM197507312930513google scholar: lookup
  55. McGowan CM, Frost R, Pfeiffer DU, Neiger R. Serum insulin concentrations in horses with equine Cushing's syndrome: response to a cortisol inhibitor and prognostic value.. Equine Vet J 2004 Apr;36(3):295-8.
    pubmed: 15147141doi: 10.2746/0425164044877288google scholar: lookup
  56. Tadros EM, Fowlie JG, Refsal KR, Marteniuk J, Schott HC 2nd. Association between hyperinsulinaemia and laminitis severity at the time of pituitary pars intermedia dysfunction diagnosis.. Equine Vet J 2019 Jan;51(1):52-56.
    pubmed: 29761574doi: 10.1111/evj.12963google scholar: lookup
  57. Jacobson GA, Pirie A, Edwards S, Hughes KJ, Rendle DI, Davies NW. Determination of pergolide in horse plasma by UPLC-MS/MS for pharmacokinetic applications.. J Pharm Biomed Anal 2014 Jun;94:54-7.
    pubmed: 24549007doi: 10.1016/j.jpba.2014.01.016google scholar: lookup

Citations

This article has been cited 14 times.
  1. Clark BL, Bamford NJ, Stewart AJ, McCue ME, Rendahl A, Bailey SR, Bertin FR, Norton EM. Evaluation of an HMGA2 variant contribution to height and basal insulin concentrations in ponies. J Vet Intern Med 2023 May-Jun;37(3):1186-1192.
    doi: 10.1111/jvim.16723pubmed: 37148171google scholar: lookup
  2. 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).
    doi: 10.3390/vetsci9100572pubmed: 36288186google scholar: lookup
  3. Kirkwood NC, Hughes KJ, Stewart AJ. Pituitary Pars Intermedia Dysfunction (PPID) in Horses. Vet Sci 2022 Oct 10;9(10).
    doi: 10.3390/vetsci9100556pubmed: 36288169google scholar: lookup
  4. Humphreys S, Kass PH, Magdesian KG, Goodrich E, Berryhill E. Seasonal variation of endogenous adrenocorticotropic hormone concentrations in healthy non-geriatric donkeys in Northern California. Front Vet Sci 2022;9:981920.
    doi: 10.3389/fvets.2022.981920pubmed: 36032308google scholar: lookup
  5. Hinrichsen SL, Yuen KY, Dryburgh EL, Bertin FR, Stewart AJ. Short-Term Effects of Temperature and Thyrotropin-Releasing Hormone Stimulation on Adrenocorticotropin Stability in Horses. Animals (Basel) 2022 Jan 28;12(3).
    doi: 10.3390/ani12030324pubmed: 35158648google scholar: lookup
  6. Thane K, Uricchio C, Frank N. Effect of early or late blood sampling on thyrotropin releasing hormone stimulation test results in horses. J Vet Intern Med 2022 Mar;36(2):770-777.
    doi: 10.1111/jvim.16362pubmed: 35049089google scholar: lookup
  7. 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 Nov;35(6):2885-2890.
    doi: 10.1111/jvim.16281pubmed: 34642962google scholar: lookup
  8. Hicks GR, Fraser NS, Bertin FR. Changes Associated with the Peri-Ovulatory Period, Age and Pregnancy in ACTH, Cortisol, Glucose and Insulin Concentrations in Mares. Animals (Basel) 2021 Mar 20;11(3).
    doi: 10.3390/ani11030891pubmed: 33804751google scholar: lookup
  9. Goodrich EL, Llanos-Soto SG, Ivanek R, Pinn-Woodcock T, Frye E, Wells A, Purdy SR, Berryhill E, Place NJ. Both Season and Equid Type Affect Endogenous Adrenocorticotropic Hormone Concentrations in Healthy Donkeys, Mules and Hinnies in the United States. Animals (Basel) 2026 Jan 16;16(2).
    doi: 10.3390/ani16020290pubmed: 41594480google scholar: lookup
  10. Parmantier S, Kyriazopoulou P, McClendon M, Adams A, Murphy BA. Influence of Extended Photoperiod Using Blue Light Masks on Hypertrichosis, Coat Condition and General Health Parameters in Horses with Pituitary Pars Intermedia Dysfunction. Animals (Basel) 2025 Oct 5;15(19).
    doi: 10.3390/ani15192905pubmed: 41096500google scholar: lookup
  11. Menzies-Gow NJ. Equine Pituitary Pars Intermedia Dysfunction. Vet Sci 2025 Aug 20;12(8).
    doi: 10.3390/vetsci12080780pubmed: 40872730google scholar: lookup
  12. 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.
    doi: 10.1111/jvim.70047pubmed: 40048369google scholar: lookup
  13. Wang W, Gibson J, Horsman S, Mikkelsen D, Bertin FR. Characterization and comparison of fecal microbiota in horses with pituitary pars intermedia dysfunction and age-matched controls. J Vet Intern Med 2025 Jan-Feb;39(1):e17288.
    doi: 10.1111/jvim.17288pubmed: 39853825google scholar: lookup
  14. Viviani P, Lavado RA, Chavarria NH, Ragno VM, Montgomery JB. Spring and fall blood concentrations of adrenocorticotropic hormone, insulin, and thyroxine in healthy horses in Saskatchewan. Can Vet J 2024 Apr;65(4):335-342.
    pubmed: 38562984
Subscribe to our newsletter
Join 99,780 horse owners like you who receive our email updates on horse health and nutrition.