Cover American Journal of Veterinary Research
American Journal of Veterinary Research
ISSN:
0002-9645
Publication Date:
01 May 2015

  • 1. Beech J, Boston R, Lindborg S, et al. 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; 231: 417–426.

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  • 2. 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; 45: 74–79.

    • Search Google Scholar
    • Export Citation

  • 3. Ireland JL, Clegg PD, McGowan CM, et al. Disease prevalence in geriatric horses in the United Kingdom: veterinary clinical assessment of 200 cases. Equine Vet J 2012; 44: 101–106.

    • Search Google Scholar
    • Export Citation

  • 4. Donaldson MT, LaMonte BH, Morresey P, et al. Treatment with pergolide or cyproheptadine of pituitary pars intermedia dysfunction (equine Cushing's disease). J Vet Intern Med 2002; 16: 742–746.

    • Search Google Scholar
    • Export Citation

  • 5. Perkins GA, Lamb S, Erb HN, et al. Plasma adrenocorticotropin (ACTH) concentrations and clinical response in horses treated for equine Cushing's disease with cyproheptadine or pergolide. Equine Vet J 2002; 34: 679–685.

    • Search Google Scholar
    • Export Citation

  • 6. Beech J, Garcia M. Hormonal response to thyrotropin-releasing hormone in healthy horses and in horses with pituitary adenoma. Am J Vet Res 1985; 46: 1941–1943.

    • Search Google Scholar
    • Export Citation

  • 7. 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; 30: 276–288.

    • Search Google Scholar
    • Export Citation

  • 8. Coupland NJ, Bailey JE, Glue P, et al. The cardiovascular and subjective effects of thyrotropin releasing hormone (TRH) and a stable analogue, dimethyl proline-TRH, in healthy volunteers. Br J Clin Pharmacol 1995; 40: 223–229.

    • Search Google Scholar
    • Export Citation

  • 9. Li WI, Chen CL, Tiller AA, et al. Effects of thyrotropin-releasing hormone on serum concentrations of thyroxine and triiodothyronine in healthy, thyroidectomized, thyroxine-treated, and propylthiouracil-treated dogs. Am J Vet Res 1986; 47: 163–169.

    • Search Google Scholar
    • Export Citation

  • 10. Tomsa K, Glaus TM, Kacl GM, et al. Thyrotropin-releasing hormone stimulation test to assess thyroid function in severely sick cats. J Vet Intern Med 2001; 15: 89–93.

    • Search Google Scholar
    • Export Citation

  • 11. Donaldson MT, McDonnell SM, Schanbacher BJ, et al. 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; 19: 217–222.

    • Search Google Scholar
    • Export Citation

  • 12. McFarlane D, Donaldson MT, McDonnell SM, et al. Effects of season and sample handling on measurement of plasma alpha-melanocyte-stimulating hormone concentrations in horses and ponies. Am J Vet Res 2004; 65: 1463–1468.

    • Search Google Scholar
    • Export Citation

  • 13. Place NJ, McGowan CM, Lamb SV, et al. Seasonal variation in serum concentrations of selected metabolic hormones in horses. J Vet Intern Med 2010; 24: 650–654.

    • Search Google Scholar
    • Export Citation

  • 14. Diez de Castro E, Lopez I, Cortes B, et al. 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; 48: 77–83.

    • Search Google Scholar
    • Export Citation

  • 15. Orth DN, Holscher MA, Wilson MG, et al. Equine Cushing's disease: plasma immunoreactive proopiolipomelanocortin peptide and cortisol levels basally and in response to diagnostic tests. Endocrinology 1982; 110: 1430–1441.

    • Search Google Scholar
    • Export Citation

  • 16. Beech J, Boston R, Lindborg S. Comparison of cortisol and ACTH responses after administration of thyrotropin releasing hormone in normal horses and those with pituitary pars intermedia dysfunction. J Vet Intern Med 2011; 25: 1431–1438.

    • Search Google Scholar
    • Export Citation

  • 17. McFarlane D, Miller LM, Craig LE, et al. Agreement in histologic assessments of the pituitary pars intermedia in aged horses. Am J Vet Res 2005; 66: 2055–2059.

    • Search Google Scholar
    • Export Citation

  • 18. Davis JL, Kirk LM, Davidson GS, et al. Effects of compounding and storage conditions on stability of pergolide mesylate. J Am Vet Med Assoc 2009; 234: 385–389.

    • Search Google Scholar
    • Export Citation

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Editorial Type:
Endocrinology

Evaluation of a thyrotropin-releasing hormone solution stored at room temperature for pituitary pars intermedia dysfunction testing in horses

Lindsay Goodale DVM1, Nicholas Frank DVM, PhD2, Pilar Hermida DVM3, and Sarah D'Oench DVM4
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  • 1 Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536.
  • | 2 Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536.
  • | 3 Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536.
  • | 4 Massachusetts Equine Clinic, 75 Locust St, Uxbridge, MA 01569.
DOI:
https://doi.org/10.2460/ajvr.76.5.437
Volume/Issue:
Volume 76: Issue 5
Online Publication Date:
01 May 2015
Restricted access
Reprints and Permissions Purchase Article

Abstract

OBJECTIVE To determine whether plasma ACTH concentrations vary following administration of a thyrotropin-releasing hormone (TRH) solution prepared for research purposes and stored at −20°C (rTRH) or prepared by a compounding pharmacy and stored at room temperature (approx 22°C; cTRH).

ANIMALS 34 adult horses.

PROCEDURES The study consisted of 2 experiments. In experiment 1, each horse underwent 2 TRH stimulation tests separated by 24 hours; 10 horses were administered cTRH for the first test and rTRH for the second test (group 1), 10 horses were administered rTRH for the first test and cTRH for the second test (group 2), and 10 horses were administered rTRH for both tests (group 3). Plasma ACTH concentrations were measured at 0 (baseline) and 30 minutes after TRH administration and the delta ACTH responses (change in ACTH concentration after TRH administration) were calculated. In experiment 2, the design was the same as that for experiment 1 except there were 14 days between tests, ACTH was measured at 0 and 10 minutes after TRH administration, and 11, 9, and 10 horses were assigned to groups 1, 2, and 3, respectively.

RESULTS Adverse effects associated with TRH administration included transient coughing and yawning. In experiment 1, the median delta ACTH response for the second test was significantly lower than that for the first test for all groups. In experiment 2, the median delta ACTH response did not differ significantly between the first and second tests for any group, ACTH concentrations after rTRH administration were positively correlated (rs = 0.95) with those after cTRH administration, and the mean ± SD bias in post-TRH ACTH concentration between rTRH and cTRH was 2.9 ± 12.4 pg/mL.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that the TRH stimulation test should not be repeated within 24 hours, and cTRH solution stored at room temperature could be used to effectively perform TRH stimulation testing in horses.

Contributor Notes

Dr. Goodale's present address is Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

Address correspondence to Dr. Frank (nicholas.frank@tufts.edu).