Implications of urine F2-isoprostane metabolite concentration in horses with colic and its potential use as a predictor for surgical intervention

Reasons for performing study: F2-isoprostanes have been used extensively to quantify lipid peroxidation in association with risk factors in various diseases. Horses with colic may have intestinal ischaemia and/or inflammation characterised by oxidative stress and increased production of isoprostanes. Objectives: To gather preliminary data regarding the feasibility of using urine F2-isoprostanes and isoprostane metabolites as early screening tools for the presence of gastrointestinal disease requiring surgical intervention in horses and ultimately develop a stall-side test capable of identifying these horses as early as possible for timely referral. Methods: Concentrations of urine isoprostane and isoprostane metabolite were determined by mass spectroscopy and normalised to urine creatinine (Cr) concentrations in urine samples from 42 healthy control horses and 43 horses with gastrointestinal pain or colic. Results: Horses with colic were treated medically (n = 21) or surgically (n = 22). Mean ± s.d. concentrations of urine isoprostane and isoprostane metabolite were significantly higher in horses with colic (2.94 ± 1.69 and 0.31 ± 0.22ng/mg Cr, respectively), compared to control horses (1.89 ± 1.39 and 0.22 ± 0.08ng/mg Cr, respectively). Mean urine isoprostane metabolite concentrations were significantly higher in horses undergoing surgery (0.38 ± 0.28ng/mg Cr) compared to controls and medical colics (0.26 ± 0.11ng/mg Cr). Nonsurvivors had significantly higher mean urine isoprostane metabolite concentrations (0.47 ± 0.39ng/mg Cr) than control or surviving colic horses (0.29 ± 0.24ng/mg Cr). Conclusions: Measurement of urine isoprostane metabolite concentration may be a useful prognostic indicator in equine colic. Potential relevance: Urine isoprostane metabolites may aid in early recognition of surgical colic. Isoprostanes are a potential therapeutic target to prevent further systemic and gastrointestinal tissue injury in horses with colic.