Autor: Isabel Raabe

In the present work, a model for the prognosis of meconium impaction was devel-oped, offering a component to the attending vet – also regarding economical aspects – for a best possible prediction of disease outcome to supplement an otherwise pro-found therapeutic decision. To this end, three binary variables survival, postoperative wound healing deficit and occurrence of further colics during the first year of age were considered. The medical records of 134 foals, that were treated between 2005 and 2013 at the Clinic for Obstetrics, Gynaecology and Andrology of Large and Small Animals at the University of Giessen concerning meconium impaction, were reviewed. At presenta-tion, a detailed medical history and physical examination were conducted in a stand-ardised process and laboratory parameters were gathered. Further blood analyses followed throughout treatment. The data also included information about mares, therapy, occurrence of complications, duration of stay and the condition of the patients at the point of discharge. 52 owners of the treated foals could be interviewed by telephone on the further development. The following numbers convey a clinical picture of the patient population: - 67 % (90 foals) male and 33 % (44 foals) female neonates - 19 % (26 foals) born with dystocia - 21 % (28 foals) premature - 69 % (92 foals) developed symptoms on the first day - 64 % (86 foals) were hospitalised on the first day - 58 % (77 foals) showed colic symptoms - 66 % (89 foals) meconium egestion was observed before presentation - 78 % (104 foals) had been pre-treated - For 83 % (110 foals) digital rectal palpation of meconium was possible - 71 % (96 foals) had ability to stand - 33 % (44 foals) in good general condition - 68 % (91 foals) had one or more comorbidities - Therapy: 62 % (83 foals) only conservative treatment, 35 % (47 foals) surgical treatment, 1,5 % (2 foals) without therapy (both deceased) - 39 % (52 foals) showed complications after treatment - Outcome: 78 % (105 foals) discharged healthy, 1,5 % (2 foals) discharged not healthy, 20 % (26 foals) euthanised or deceased, 1 foal not reported The prognosis model was attained using a multivariable stepwise logistic regression model. The result is a prognosis function that states the probability of the dependent variable subject to characteristic values of a foal’s isolated influential variables. About the dependent variable survival: From the 59 attributes, the logistic regression forward-selectively isolated prematurity (mature/ premature), base excess (mmol / l), respiratory rate (breaths per minute) and platelets (G / l) as the strongest influential variables. The regression equation was: The equation reveals that a premature foal has a seven times higher chance of de-ceasing than a mature foal and that the probability of survival grows with an increase of the remaining three influential variables. More specifically, - A one unit (1 mmol / l) increase of base excess decreases the chance of deceas-ing by a factor of 0.866, - The increase of the respiratory rate by one breath per minute decreases the chance of deceasing by a factor of 0.949, - The increase of platelets of 10 G/l decreases the chance of deceasing by a factor of 0.911. To increase practicability, one-dimensional projections and tables were provided for every influential variable as further means of documentation of the results. The following statements regarding the influence of further attributes resulted from correlation analyses: - 90 % of mature foals survive, - 57 % of premature foals decease - 86 % of foals with the ability to stand (alone or with help) survive - 62 % of foals without the ability to stand decease, - 74 % of foals with comorbidity survive, - 95 % of foals without comorbidity survive. The attributes sex and maturity affect survival as follows: - 15 % of male and 30 % of female foals decease, - 18 % of male and 32,5 % of female foals are premature, - 26 % of male premature and 62 % of female premature foals decease Laboratory parameters with significant influence on the survival of a foal showed: Deceased foals had a (mean values in parentheses) - 14 % higher potassium concentration (3.7 and 4.2 mmol/l respectively), - 79 % higher lactate concentration (converted 2.8 and 5.0 mmol/l), - 8 % higher partial pressure of carbon dioxide (6.8 and 7.33 kPa), - 7 % higher calcium concentration (1.49 and 1.6 mmol/l), - 36 % lower immunglobulin g concentration (642 and 410 mg/dl), - 117 % lower base excess (3.22 and -0.558 mmol/l), - 17 % lower platelets count (327 and 270 G/l), - 27 % lower count of white blood cells (8.5 and 6.2 G/l) and - 9 % lower hydrogen carbonate concentration (28.6 and 26.1 mmol/l) First symptoms of meconium impaction on average occurred after a lifetime of 8:50 hours for surviving and 4:13 hours for deceased foals. The datasets of a total of 108 foals served as the basis for the measurement of inter-nal validity of the regression function. The remaining ones were not suitable to this end due to partially missing data. Three χ2-based test statistics and an AUC-value of 0.8739 (area under the ROC-curve) attest the model a good to very good fit to the sample. The external validity, i.e. the validity of the prognosis for e.g. equal data from another clinic or veterinary practice with a different cross section of patients, was not assessed. The prognosis function provided the best prognosis values for a cut-off score of 0.71. From this, the following characteristic values arose: - sensitivity = 0.71 - specificity = 0.95 - negative predictive value = 0.95 - positive predictive value = 0.71. The regression analysis of wound healing deficit concluded without result. No sig-nificant predictor could be found. The logistic function for the prognosis of colics within the first year of life includes heart rate (at the time of presentation in the clinic due to meconium impaction) and the age of the mare as influential variables. This result is being discarded as medically not plausible.