Diagnostic testing for pituitary pars intermedia dysfunction in horses.

N. O. Dybdal, K. M. Hargreaves, John E Madigan, D. H. Gribble, P. C. Kennedy, G. H. Stabenfeldt

Research output: Contribution to journalArticle

131 Citations (Scopus)

Abstract

Pituitary pars intermedia dysfunction is a slowly progressive disorder that afflicts most breeds of horses. Because it shares features with human Cushing disease, it has been referred to as equine Cushing disease. A variety of tests of pituitary-adrenocortical function were performed on horses with evidence of pituitary pars intermediate dysfunction, and results were compared with those in healthy control horses. Diurnal variations in plasma cortisol concentration were not statistically different between control horses and those with pituitary pars intermedia dysfunction. An ACTH stimulation (1 U of natural ACTH gel/kg of body weight, IM) test or a combined dexamethasone suppression test (10 mg, IM) and ACTH stimulation (100 mg of synthetic ACTH, IV) test also failed to distinguish horses with pituitary pars intermedia dysfunction from control horses. A significant (P < 0.001) dose-related suppression of cortisol concentration in response to increasing doses (5, 10, 20, and 40 micrograms/kg) of dexamethasone was observed in control horses but not in those with pituitary pars intermedia dysfunction. On the basis of plasma cortisol concentration, the dexamethasone suppression test, using 40 micrograms/kg, whether initiated at 5 PM with sample collection at 15 (8 AM) and 19 (12 PM) hours after dexamethasone administration, or initiated at 12 AM with sample collection at 8 (8 AM), 12 (12 PM), 16 (4 PM), 20 (8 PM), and 24 (12 AM) hours after dexamethasone administration, reliably distinguished between control horses and those with pituitary pars intermedia dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Original languageEnglish (US)
Pages (from-to)627-632
Number of pages6
JournalJournal of the American Veterinary Medical Association
Volume204
Issue number4
StatePublished - Feb 15 1994

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Intermediate Pituitary Gland
Horses
dexamethasone
horses
Dexamethasone
corticotropin
testing
Adrenocorticotropic Hormone
Cushing syndrome
cortisol
Hydrocortisone
Pituitary ACTH Hypersecretion
Pituitary Function Tests
Horse Diseases
Cosyntropin
horse breeds
dosage
diurnal variation
Gels
Body Weight

ASJC Scopus subject areas

  • veterinary(all)

Cite this

Dybdal, N. O., Hargreaves, K. M., Madigan, J. E., Gribble, D. H., Kennedy, P. C., & Stabenfeldt, G. H. (1994). Diagnostic testing for pituitary pars intermedia dysfunction in horses. Journal of the American Veterinary Medical Association, 204(4), 627-632.

Diagnostic testing for pituitary pars intermedia dysfunction in horses. / Dybdal, N. O.; Hargreaves, K. M.; Madigan, John E; Gribble, D. H.; Kennedy, P. C.; Stabenfeldt, G. H.

In: Journal of the American Veterinary Medical Association, Vol. 204, No. 4, 15.02.1994, p. 627-632.

Research output: Contribution to journalArticle

Dybdal, NO, Hargreaves, KM, Madigan, JE, Gribble, DH, Kennedy, PC & Stabenfeldt, GH 1994, 'Diagnostic testing for pituitary pars intermedia dysfunction in horses.', Journal of the American Veterinary Medical Association, vol. 204, no. 4, pp. 627-632.
Dybdal NO, Hargreaves KM, Madigan JE, Gribble DH, Kennedy PC, Stabenfeldt GH. Diagnostic testing for pituitary pars intermedia dysfunction in horses. Journal of the American Veterinary Medical Association. 1994 Feb 15;204(4):627-632.
Dybdal, N. O. ; Hargreaves, K. M. ; Madigan, John E ; Gribble, D. H. ; Kennedy, P. C. ; Stabenfeldt, G. H. / Diagnostic testing for pituitary pars intermedia dysfunction in horses. In: Journal of the American Veterinary Medical Association. 1994 ; Vol. 204, No. 4. pp. 627-632.
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