Azaperone and sudden death of drive net-captured southern chamois

The use of tranquilizers in the capture of southern chamois (Rupicapra pyrenaica) for scientific and/or management purposes (collection of samples, marking, translocations) was studied to improve animal welfare during capture operations. We used clinical findings and a statistical approach to analyze the causes of six incidences of mortality during captures using drive nets and tranquilizers in this species. Hematology and serum biochemistry, pathology, the use of tranquilizers and their dosages, the number of people involved in the capture of the chamois, and the location were all taken into account. The selection of candidate models to explain mortality was conducted using the theoretic information approach. Both observational findings and the models selected suggested that high doses of azaperone and to a lesser extent haloperidol had an effect on mortality rates. The higher mean serum lactate concentrations found in the chamois that died suggests that fatigue levels increased drug sensitivity and provoked the appearance of adverse effects, thereby increasing the probability of death. We conclude that butyrophenones—and especially azaperone—have a low safety margin in the southern chamois, contrary to what has been described for other species.