Prognostic indicators associated with early mortality of wild raptors admitted to a wildlife rehabilitation centre in Spain

Background: Assessment of the prognostic indicators of wildlife casualties is critical in wildlife rehabilitation practice, to optimize the use of economical resources, and to protect animal welfare. Few studies have been conducted in this field. Objective: To identify the prognostic indicators associated with raptor mortality during the first week of hospitalization. Animals and methods: Complete medical records of 1722 wild raptor cases admitted to a wildlife rehabilitation centre from 1995 to 2007 were used. Regression models were created to determine mortality-related factors for different variables (order, sex, body condition (BC), clinical signs, and available haematological and biochemical parameters). Results: In the bivariate analysis, the presence of nervous (OR = 11.9, 95%CI:5.1-27.6) or musculoskeletal (OR = 12.1, 95%CI:5.8-25.3) signs, a poor BC (OR = 32.9, 95%CI:19-81.2), and low values of packed cell volume (PCV), haemoglobin or total solids (TS), were all associated with early mortality. After adjusting variables in the multivariate model, BC was excluded due to co-linearity with other variables, and alteration of the nervous system was the only significant risk factor (OR = 4.0; 95%CI:1.9-8.8). In species specific analysis, poor prognosis was related to neurological signs in Athene noctua, poor BC in Strix aluco, trauma in Acciptiter nisus and Tyto alba, low PCV in Buteo buteo and Falco tinnunculus and low TS in Falco tinnunculus. Conclusions: Raptors with a poor BC, low values of PCV and those presenting with neurological signs, had the highest risk of dying in the first days of admittance. Thus, either medical care or humane euthanasia for poor prognosis should be performed to address animal welfare.