Acta vet. scand. 2004, 45, 109-118. Evaluation of Clinical and Laboratory Variables as Prognostic Indicators in Hospitalised Gastrointesti- nal Colic Horses By Carl F. Ihler1, Jostein Larsen Venger1 and Eystein Skjerve2 1Department of Large Animal Clinical Sciences, and 2Department of Pharmacology, Microbiology and Food Hygiene; The Norwegian School of Veterinary Science, Oslo, Norway. Ihler CF, Larsen J and Skjerve E: Evaluation of clinical and laboratory variables as prognostic indicators in hospitalised gastrointestinal colic horses. Acta vet. scand. 2004, 45, 109-118. – The present prospective study included 106 horses referred to the Department of Large Animal Sciences, The Norwegian School of Veterinary Sci- ence, as non-responders to the initial colic treatment in general practise. In 14 of these cases a required surgical treatment was not performed due to economical or other rea- sons and were excluded from the study. Clinical and laboratory data were obtained at the arrival in the hospital. The outcome for all analyses was survival/ non-survival. A mul- tivariable logistic regression was performed. The analyses were used in medically (46 horses) and surgically treated cases (46 horses) separately. The same analyses were also run for all 92 horses in a simulated "ﬁeld" situation, where only clinical variables and D-dimer values were included. The fraction of survivors was 78% in the medical and 48% in the surgical cases. In total 63% of the horses survived. In the ﬁnal multivariable logistic regression model packed cell volume (PCV) was the only important predictor for medically treated cases, and heart rate and presence of hyperaemic or cyanotic mu- cous membranes were the predictors in the surgically treated cases as well as in the sim- ulated "ﬁeld" situation. In conclusion, traditional variables as heart rate, mucous mem- branes and PCV were the important predictors for the outcome in hospitalised colic cases. horse; colic; prognosis; clinical and laboratory variables; hospital; logistic regres- sion; epidemiology. Introduction Equine colic caused by gastrointestinal disor- ders is often encountered in general equine practise and may lead to severe clinical condi- tions and death. The incidence of colic is esti- mated in several studies. From USA Kaneene et al. (1997) and Tinker et al. (1997) reported an incidence of 3.5 and 10.5 colic cases per 100 horse-years, respectively. From Norway Larsen & Flåøyen (1997) estimated the incidence to be 4.8 colic cases per 100 horse-years. The case fatality rate is by Kaneene et al. (1997) and Tin- ker et al. (1997) reported to be 13 and 7%, re- spectively. Acute cases often need immediate surgical treatment. Such treatment is expensive and the mortality is relatively high, reported to be be- tween 31 and 44% in different studies (Morris 1991, Sandholm et al. 1995, Kaneene et al. 1997). In general, a correct diagnosis is necessary to predict a reliable prognosis. In colic cases, how- ever, a correct clinical diagnosis of the site and Acta vet. scand. vol. 45 no. 1-2, 2004