• 1. Millington WR, Dybdal NO, Dawson R Jr, et al. Equine Cushing's disease: differential regulation of β-endorphin processing in tumors of the intermediate pituitary. Endocrinology 1988; 123: 15981604.

    • Search Google Scholar
    • Export Citation
  • 2. Alexander SL, Irvine CHG, Donald RA. Dynamics of the regulation of the hypothalamo-pituitary-adrenal (HPA) axis determined using a nonsurgical method of collecting pituitary venous blood from horses. Front Neuroendocrinol 1996; 17: 150.

    • Search Google Scholar
    • Export Citation
  • 3. McFarlane D. Equine pituitary pars intermedia dysfunction. Vet Clin Equine 2011; 27: 93113.

  • 4. van der Kolk JH, Wensing T, Kalsbeek HC, et al. Laboratory diagnosis of equine pituitary pars intermedia adenoma. Domest Anim Endocrinol 1995; 2: 3539.

    • Search Google Scholar
    • Export Citation
  • 5. Couetil L, Paradis MR, Knoll J. Plasma adrenocorticotropin concentration in healthy horses and horses with clinical signs of hyperadrenocorticism. J Vet Intern Med 1996; 10: 16.

    • Search Google Scholar
    • Export Citation
  • 6. Lee ZY, Zylstra R, Haritou SJ. The use of adrenocorticotrophic hormone as a potential biomarker of pituitary pars intermedia dysfunction in horses. Vet J 2010; 185: 5861.

    • Search Google Scholar
    • Export Citation
  • 7. McGowan TW, Pinchbeck GP, McGowan 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; 45: 6673.

    • Search Google Scholar
    • Export Citation
  • 8. Irvine CHG, Alexander SL. A novel technique for measuring hypothalamic and pituitary hormone secretion rates from collection of pituitary venous effluent in the normal horse. J Endocrinol 1987; 113: 183192.

    • Search Google Scholar
    • Export Citation
  • 9. McConaghy FF, Hales JR, Rose RJ, et al. Selective brain cooling in the horse during exercise and environmental heat stress. J Appl Physiol 1995; 79: 18491854.

    • Search Google Scholar
    • Export Citation
  • 10. Alexander SL, Irvine CHG, Donald RA. Short-term secretion patterns of corticotropin-releasing hormone, arginine vasopressin and ACTH as shown by intensive sampling of pituitary venous blood from horses. Neuroendocrinology 1994; 60: 225236.

    • Search Google Scholar
    • Export Citation
  • 11. Taylor PM. Equine stress responses to anaesthesia. Br J Anaesth 1989; 63: 702709.

  • 12. Luna SPL, Taylor PM. Pituitary-adrenal activity and opioid release in ponies during thiopentone/halothane anaesthesia. Res Vet Sci 1995; 58: 3541.

    • Search Google Scholar
    • Export Citation
  • 13. Taylor PM. Stress responses in ponies during halothane or isoflurane anaesthesia after induction with thiopentone or xylazine/ketamine. J Vet Anaesth 1991; 18: 814.

    • Search Google Scholar
    • Export Citation
  • 14. Biller BMK, Grossman AB, Stewart PM, et al. Treatment of adrenocorticotropin-dependent Cushing's syndrome: a consensus statement. J Clin Endocrinol Metab 2008; 93: 24542462.

    • Search Google Scholar
    • Export Citation
  • 15. Miller MA, Pardo ID, Jackson LP, et al. Correlation of pituitary histomorphometry with adrenocorticotrophic hormone response to domperidone administration in the diagnosis of equine pituitary pars intermedia dysfunction. Vet Pathol 2008; 45: 2638.

    • Search Google Scholar
    • Export Citation
  • 16. Cuevas-Ramos D, Fleseriu M. Treatment of Cushing's disease: a mechanistic update. J Endocrinol 2014;223:R19–R39.

  • 17. Lau D, Rutledge C, Aghi MK. Cushing's disease: current medical therapies and molecular insights guiding future therapies. Neurosurg Focus 2015; 38: 110.

    • Search Google Scholar
    • Export Citation
  • 18. Sakes A, Arkenbout EA, Jelínek F, et al. Design of an endovascular morcellator for the surgical treatment of equine Cushing's disease. Vet Q 2015; 35: 165169.

    • Search Google Scholar
    • Export Citation
  • 19. Wilson DV, Schott HC, Robinson NE, et al. Response to nasopharyngeal oxygen administration in horses with lung disease. Equine Vet J 2006; 38: 219223.

    • Search Google Scholar
    • Export Citation
  • 20. Perkins GA, Lamb S, Erb H, 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: 679685.

    • Search Google Scholar
    • Export Citation
  • 21. Dohoo I, Martin W, Stryhn H. Model-building strategies. In: Veterinary epidemiologic research. 2nd ed. Charlottetown, PE, Canada: VER Inc, 2012;365–394.

    • Search Google Scholar
    • Export Citation
  • 22. Johnson ML, Virostko A, Veldhuis JD, et al. Deconvolution analysis as a hormone pulse-detection algorithm. Methods Enzymol 2004; 384: 4054.

    • Search Google Scholar
    • Export Citation
  • 23. Dzikiti TB, Hellebrekers LJ, van Dijk P. Effects of intravenous lidocaine on isoflurane concentration, physiological parameters, metabolic parameters and stress-related hormones in horses undergoing surgery. J Vet Med A Physiol Pathol Clin Med 2003; 50: 190195.

    • Search Google Scholar
    • Export Citation
  • 24. Taylor PM. Adrenocortical and metabolic responses to dobutamine infusion during halothane anesthesia in ponies. J Vet Pharmacol Ther 1998; 21: 282287.

    • Search Google Scholar
    • Export Citation
  • 25. Taylor PM. The stress response to anaesthesia in ponies: barbiturate anaesthesia. Equine Vet J 1990; 22: 307312.

  • 26. Brodbelt DC, Harris J, Taylor PM. Pituitary-adrenocortical effects of methoxamine infusion on halothane anaesthetised ponies. Res Vet Sci 1998; 65: 119123.

    • Search Google Scholar
    • Export Citation
  • 27. Taylor PM. Effects of hypercapnia on endocrine and metabolic responses to anaesthesia in ponies. Res Vet Sci 1998; 65: 4146.

  • 28. Khanna AK, McDonnell WN, Dyson DH, et al. Cardiopulmonary effects of hypercapnia during controlled positive pressure ventilation in the horse. Can J Vet Res 1995; 59: 213221.

    • Search Google Scholar
    • Export Citation
  • 29. Koenig J, McDonnell WN, Valverde A. Accuracy of pulse oximetry and capnography in healthy and compromised horses during spontaneous and controlled ventilation. Can J Vet Res 2003; 67: 169174.

    • Search Google Scholar
    • Export Citation
  • 30. Oak ZC, Young KC, Doo IL, et al. Intraoperative mild hypothermia does not increase plasma concentrations of stress hormones during neurosurgery. Can J Anaesth 2001; 48: 815818.

    • Search Google Scholar
    • Export Citation
  • 31. Robertson SA. Some metabolic and hormonal changes associated with general anesthesia and surgery in the horse. Equine Vet J 1987; 19: 288294.

    • Search Google Scholar
    • Export Citation
  • 32. Alexander SL, Irvine CHG. The effect of the alpha-2-adrenergic agonist, clonidine, on secretion patterns and rates of adrenocorticotropic hormone and its secretagogues in the horse. J Neuroendocrinol 2000; 12: 8788.

    • Search Google Scholar
    • Export Citation
  • 33. Raekallio M, Leino A, Vainio O, et al. Sympatho-adrenal activity and the clinical sedative effect of detomidine in horses. Equine Vet J Suppl 1992; 11: 6668.

    • Search Google Scholar
    • Export Citation
  • 34. Carroll GL, Matthews NS, Hartsfield SM, et al. The effects of detomidine and its antagonism with tolazoline on stress related hormones, metabolites, physiologic responses and behavior in awake ponies. Vet Surg 1997; 26: 6977.

    • Search Google Scholar
    • Export Citation
  • 35. Ambrisko TD, Hikasa Y. Neurohormonal and metabolic effects of medetomidine compared with xylazine in Beagle dogs. Can J Vet Res 2002; 66: 4249.

    • Search Google Scholar
    • Export Citation
  • 36. Dias BP, De Araujo MA, Deschk M, et al. Effects of an intravenous infusion of butorphanol in isoflurane-anesthetized horses on cardiorespiratory parameters, recovery quality, gastrointestinal motility and serum cortisol concentrations. Acta Cir Bras 2014; 29: 801806.

    • Search Google Scholar
    • Export Citation
  • 37. Ruane-O'Hora T, Hall WJ, Markos F. The effect of alphaxalone-alphadolone, propofol, and pentobarbitone anaesthesia on the β-endorphin and ACTH response to haemorrhage in the pig. Can J Physiol Pharmacol 2011; 89: 521526.

    • Search Google Scholar
    • Export Citation
  • 38. Luna SP, Taylor PM. Cortisol, peptides and catecholamines in cerebrospinal fluid, pituitary effluent and peripheral blood of ponies. Equine Vet J 1998; 30: 166169.

    • Search Google Scholar
    • Export Citation

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Effects of anesthesia with isoflurane on plasma concentrations of adrenocorticotropic hormone in samples obtained from the cavernous sinus and jugular vein of horses

James L. Carmalt VetMB, MVetSC1, Tanya Duke-Novakovski BVMC, MSC2, Harold C. Schott II DVM, PhD3, and Johannes H. van der Kolk DVM, PhD4
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  • 1 Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, SK S7N 5B4 Canada.
  • | 2 Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, SK S7N 5B4 Canada.
  • | 3 Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824.
  • | 4 Department of Clinical Veterinary Medicine, Swiss Institute for Equine Medicine, Vetsuisse Faculty, University of Bern and Agroscope, 3012 Bern, Switzerland.

Abstract

OBJECTIVE To determine effects of anesthesia on plasma concentrations and pulsatility of ACTH in samples obtained from the cavernous sinus and jugular vein of horses.

ANIMALS 6 clinically normal adult horses.

PROCEDURES Catheters were placed in a jugular vein and into the cavernous sinus via a superficial facial vein. The following morning (day 1), cavernous sinus blood samples were collected every 5 minutes for 1 hour (collection of first sample = time 0) and jugular venous blood samples were collected at 0, 30, and 60 minutes. On day 2, horses were sedated with xylazine hydrochloride and anesthesia was induced with propofol mixed with ketamine hydrochloride. Horses were positioned in dorsal recumbency. Anesthesia was maintained with isoflurane in oxygen and a continuous rate infusion of butorphanol tartrate. One hour after anesthesia was induced, the blood sample protocol was repeated. Plasma ACTH concentrations were quantified by use of a commercially available sandwich assay. Generalized estimating equations that controlled for horse and an expressly automated deconvolution algorithm were used to determine effects of anesthesia on plasma ACTH concentrations and pulsatility, respectively.

RESULTS Anesthesia significantly reduced the plasma ACTH concentration in blood samples collected from the cavernous sinus.

CONCLUSIONS AND CLINICAL RELEVANCE Mean plasma ACTH concentrations in samples collected from the cavernous sinus of anesthetized horses were reduced. Determining the success of partial ablation of the pituitary gland in situ for treatment of pituitary pars intermedia dysfunction may require that effects of anesthesia be included in interpretation of plasma ACTH concentrations in cavernous sinus blood.

Contributor Notes

Address correspondence to Dr. Carmalt (james.carmalt@usask.ca).