114 Carl F. Ihler et al. Ta bl e 4 . Final multiple logistic regression models for surgically and medically treated colic cases and "simu- lated ﬁeld situation" based upon variables presented in Table 3. Results are given as estimates (95 % conﬁdence limits) and Odds Ratio (95 % conﬁdence limits). Treatment group Variable Surgically treated cases Medically treated cases Simulated ﬁeld situation * Per increase of 10 units **Per increase of 1 unit Heart rate Abnormal mucous membranes PCV Heart rate Abnormal mucous membranes Estimate 0.11 (0.04-0.18) 2.90 (0.73-5.07) 0.20 (0.07-0.32) 0.07 (0.04-0.11) 1.18 (0.03-2.34) Odds Ratio 3.00 (1.49-6.05)* 18.23 (2.08-159) 1.22 (1.07-1.37)** 2.05 (1.62-2.88)* 3.25 (1.03-10.3) proach using the kernel smoothing graph pro- cedure in Intercooled Stata for Windows 7.0 (Stata Corporation, College Station, TX, USA). Interactions were not evaluated due to a limited number of horses. Results Fifty-eight horses (63%) of the total 92 colic cases survived. Forty-six horses where treated medically (survival 78%) and 46 were treated surgically (survival 48%). The numbers of sur- Fi g u r e 1 . Estimated probability of non-survival for medically and surgically treated colic cases based upon the ﬁnal logistic models in Table 4. For surgically treated horses the left curve represents horses with abnormal mu- cous membranes and the right curve represents horses with normal mucous membranes. Acta vet. scand. vol. 45 no. 1-2, 2004