title: Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.
abstract: BACKGROUND
  Colic remains a life-threatening condition in the horse. Ischaemia and reperfusion following correction of small intestinal strangulation may produce oxidative stress. The ability to withstand oxidative stress depends on antioxidant levels and may be linked to horse survival.
  
  
  OBJECTIVE
  To measure peripheral antioxidant levels in horses undergoing exploratory laparotomy with small intestinal strangulation.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Blood and plasma were collected from horses undergoing exploratory laparotomy for small intestinal strangulation and stored at -80°C. Controls involved non-colic horses. Total plasma glutathione was measured spectrophotometrically at 412 nm using the 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB, Ellman's reagent) reaction. Samples containing scavenger (to remove reduced glutathione, GSH) were used to measure oxidised glutathione (GSSG). Glutathione reductase (GR) activity (u/l) was measured as the rate of GSH production at 412 nm. Glutathione peroxidise (GPx) activity (u/l) was measured as the change in optical density (340 nm) following the consumption of NADPH after GSSG production. All assays were purchased from BioAssay Systems (Hayward, California). Clinical data including arterial blood gas analysis were collected on admission.
  
  
  RESULTS
  Glutathione reductase activity in horses with strangulating small intestinal lesions was significantly reduced compared to control horses (12.2 ± 1.1 u/l vs. 15.9 ± 0.8 u/l, P = 0.03, n = 6) whereas GPx activity did not significantly differ between colic and control horses (155.7 ± 48.7 u/l vs. 167.3 ± 30.1 u/l, P = 0.84, n = 6). Total glutathione, reduced or oxidised glutathione did not differ significantly between control and colic horses. A positive correlation existed between GR activity and Ca(2+) (r = 0.93) and K(+) (r = 0.75) whereas a strong negative correlation was present between GR activity and HCO3 (-) (r = -0.92) and PaCO2 (r = -0.96).
  
  
  CONCLUSIONS
  Reduced plasma glutathione reductase activity with small intestinal strangulation indicates oxidative stress and may be related to systemic electrolyte/bicarbonate abnormalities. Ethical animal research: Study approval No. VREC219a. Explicit owner informed consent for inclusion of animals in this study was not stated.
  
  
  BACKGROUND
  Supported by the School of Veterinary Sciences, University of Liverpool. Competing interests: None declared.
authors.affiliation: The Philip Leverhulme Equine Hospital, School of Veterinary Science, University of Liverpool, UK.
authors.forename: D A
authors.initials: DA
authors.lastname: Bardell
authors.affiliation: The Philip Leverhulme Equine Hospital, School of Veterinary Science, University of Liverpool, UK.
authors.forename: D C
authors.initials: DC
authors.lastname: Archer
authors.affiliation: The Philip Leverhulme Equine Hospital, School of Veterinary Science, University of Liverpool, UK.
authors.forename: P I
authors.initials: PI
authors.lastname: Milner