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Endocrine response to illness in sick horses

presence of critically-illness-related corticosteroid insufficiency or pancreatic insufficiency in horses is related to poor survival

Stewart, Allison (2018). Endocrine response to illness in sick horses. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Veterinaria, 1401-6257 ; 2018:59
ISBN 978-91-7760-258-3
eISBN 978-91-7760-259-0
[Doctoral thesis]

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Abstract

Endocrinological responses are under tight physiological control in healthy animals, with homeostatic adaptions made for diet, exercise and illness. Transient adrenal dysfunction with inadequate cortisol production, known as relative adrenal insufficiency (RAI), is a major component of critical illness–related corticosteroid insufficiency (CIRCI), which involves dysfunction of the entire HPA axis. Recognition and treatment of CIRCI improves human survival rates. Whereas a low-dose ACTH stimulation test appears to be the most sensitive method of diagnosing CIRCI in people, published doses for this test in horses were considerably higher, and the lowest dose of ACTH that will maximally stimulate the adrenal glands of horses was unknown. Critical illness is also associated with peripheral tissue insulin resistance and hyperglycaemia in many species, but insulin and glucose dynamics in spontaneously sick adult horses remains to be investigated.

The overall aim was to document changes in cortisol, ACTH, insulin and glucose in sick horses; determine if adrenal or pancreatic dysfunction occurred, and which parameters were correlated with non-survival. A secondary aim was to validate the low-dose ACTH stimulation test in healthy adult horses and neonatal foals and then determine if CIRCI could be identified in sick horses.

A dose of synthetic ACTH of 0.1 µg/kg in healthy adult horses and 0.25 µg/kg in neonatal foals resulted in maximal adrenal stimulation. In sick horses, cortisol, ACTH and ACTH/cortisol ratios were higher in non-survivors at admission. ACTH/cortisol ratios were higher in horses with systemic inflammatory response syndrome (SIRS) and those with an ischemic gastrointestinal lesion, suggesting adrenal dysfunction. Although horses with ischemic lesions had higher basal cortisol, they failed to respond to ACTH stimulation, further indicating adrenal dysfunction. RAI/CIRCI was diagnosed in 21% of sick horses and is associated with a poorer prognosis. Horses presenting with hyperglycaemia and corresponding relative hypoinsulinemia (suggestive of endocrine pancreas dysfunction) had a worse prognosis.

Authors/Creators:Stewart, Allison
Title:Endocrine response to illness in sick horses
Subtitle:presence of critically-illness-related corticosteroid insufficiency or pancreatic insufficiency in horses is related to poor survival
Alternative abstract:
LanguageAbstract
Swedish

Endokrina responser är strikt reglerade hos friska djur och anpassas efter diet, fysiskt arbete och sjukdom. Övergående binjuredysfunktion ger otillräcklig kortisolproduktion, sk ”relative adrenal insufficiency”, RAI. Detta spelar en viktig roll i sjukdomsrelaterad sekundär kortisolsvikt (”critical illness-related corticosteroid insufficiency”, CIRCI) där man har dysfunktion av hela HPA axeln. Identifiering och behandling av sekundär kortisolsvikt förbättrar överlevnaden inom humanvården. Lågdos ACTH-stimuleringstest förefaller vara det känsligaste testet för diagnos, men publicerade doser för att utföra provtagning på häst har varit betydligt högre än vad som används på humansidan. Den lägsta dos ACTH som krävs för maximal stimulering av hästens binjure har hittills varit okänd. Allvarlig sjukdom är också associerad med perifer insulinresistens och hyperglykemi på flera djurslag, men mer information om insulin- och glukosmetabolismen hos sjuka hästar behövs.

Målet med studien var att dokumentera förändringar i kortisol, ACTH, insulin och glukos hos sjuka hästar, att fastställa eventuell förekomst av binjure- eller pankreasinsufficiens, samt att undersöka vilka parametrar som kan korreleras till sämre prognos för överlevnad. Målet var också att validera ett lågdos ACTH-stimuleringstest för användning på vuxna hästar och neonatala föl, och att fastställa om CIRCI kunde detekteras hos sjuka hästar.

Syntetiskt ACTH doserat till 0,1µg/kg åt friska hästar och 0,25µg/kg åt friska neonatala föl resulterade i maximal binjurestimulering. Hos sjuka hästar som provtogs vid ankomst till klinik var kortisol, ACTH, och ACTH/kortisol kvoten högre hos de hästar som inte överlevde. ACTH/kortisol kvoten var högre hos hästar med systemiskt inflammationsrespons syndrom (SIRS) och hos hästar med ischemiska tarmlidanden, vilket indikerar binjuredysfunktion. Hästar med ischemiska skador hade också högre basala kortisolhalter, men svarade dåligt på ACTH-stimulering vilket ytterligare indikerar binjuredysfunktion. RAI/CIRCI diagnosticerades hos 21 % av de sjuka hästarna och var associerat med sämre prognos. Hästar som kom in med hyperglykemi och samtidig relativ hypoinsulinemi (överensstämmande med dysfunktion av endokrina pankreas) hade en sämre prognos för överlevnad.

Series/Journal:Acta Universitatis Agriculturae Sueciae. Veterinaria (1401-6257)
Year of publishing :22 October 2018
Depositing date:22 October 2018
Volume:2018:59
Number of Pages:138
Papers/manuscripts:
NumberReferences
IStewart, A.J.*, Behrend, E.N., Wright, J.C., Martin, L.G., Kemppainen. R.J., Busch, K.A., Hanson, R.R. (2011). Validation of a low-dose ACTH stimulation test in normal adult horses. Journal of the American Veterinary Medical Association. 239(2), 834-841.
IIStewart, A.J.*, Wright, J.C., Behrend, E.N., Martin, L.G., Kemppainen, R.J., Busch, K.A. (2013). Validation of a low-dose ACTH stimulation test in healthy neonatal foals. Journal of the American Veterinary Medical Association. 243(3), 399-405.
IIIBertin, F.R., Ruffin-Taylor, D., Stewart, A.J.* (2018). Insulin dysregulation in horses with systemic inflammatory response syndrome. Journal of Veterinary Internal Medicine. 32(4):1420-1427.
IVStewart, A.J.*, Hackett, E., Bertin, F. R., Towns, T.J. Cortisol and ACTH concentrations in horses with systemic inflammatory response syndrome. Manuscript
VStewart, A.J.*, Hackett, E., Bertin, F.R., Towns, T.J. Identification of Adrenal Dysfunction in Critically Ill Adult Horses. Manuscript
Place of Publication:Uppsala
Publisher:Department of Clinical Sciences, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-258-3
ISBN for electronic version:978-91-7760-259-0
ISSN:1401-6257
Language:English
Additional Information:Projects: I – II Birmingham Racing Commission. Project III Hoof Development and Rehabilitation Gift Fund donated by the family of Hall W. Thompson Projects IV – V: American College of Veterinary Emergency and Critical Care research award and the Morris Animal Foundation: Veterinary Student Scholar Program
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L73 Animal diseases
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 403 Veterinary Science > Clinical Science
Keywords:endocrinology, horses, adrenal, equine, inflammation, colic, CIRCI, cortisol, adrenocorticotropic hormone, ACTH stimulation, SIRS, insulin dysregulation, pancreas
URN:NBN:urn:nbn:se:slu:epsilon-e-5081
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-5081
ID Code:15720
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Clinical Sciences
Deposited By: Allison Stewart
Deposited On:23 Oct 2018 07:50
Metadata Last Modified:27 Feb 2019 03:52

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